diff --git a/Library/Homebrew/ast_constants.rb b/Library/Homebrew/ast_constants.rb
index fa31aef6ed..c6ec8eb61c 100644
--- a/Library/Homebrew/ast_constants.rb
+++ b/Library/Homebrew/ast_constants.rb
@@ -52,4 +52,4 @@ FORMULA_COMPONENT_PRECEDENCE_LIST = T.let([
   [{ name: :caveats, type: :method_definition }],
   [{ name: :plist_options, type: :method_call }, { name: :plist, type: :method_definition }],
   [{ name: :test, type: :block_call }],
-].freeze, T::Array[[{ name: Symbol, type: Symbol }]])
+].freeze, T::Array[T::Array[{ name: Symbol, type: Symbol }]])
diff --git a/Library/Homebrew/cask/dsl.rb b/Library/Homebrew/cask/dsl.rb
index 7b2d7f1bb3..22a55c4f1f 100644
--- a/Library/Homebrew/cask/dsl.rb
+++ b/Library/Homebrew/cask/dsl.rb
@@ -486,7 +486,7 @@ module Cask
     def add_implicit_macos_dependency
       return if (cask_depends_on = @depends_on).present? && cask_depends_on.macos.present?
 
-      depends_on macos: ">= :#{MacOSVersion::SYMBOLS.key MacOSVersion::SYMBOLS.values.min}"
+      depends_on macos: ">= #{MacOSVersion.new(HOMEBREW_MACOS_OLDEST_ALLOWED).to_sym.inspect}"
     end
 
     # Declare conflicts that keep a cask from installing or working correctly.
diff --git a/Library/Homebrew/cask/dsl/depends_on.rb b/Library/Homebrew/cask/dsl/depends_on.rb
index 7a5756f9c0..ddaf48698f 100644
--- a/Library/Homebrew/cask/dsl/depends_on.rb
+++ b/Library/Homebrew/cask/dsl/depends_on.rb
@@ -52,16 +52,17 @@ module Cask
         raise "Only a single 'depends_on macos' is allowed." if defined?(@macos)
 
         # workaround for https://github.com/sorbet/sorbet/issues/6860
-        first_arg = args.first&.to_s
+        first_arg = args.first
+        first_arg_s = first_arg&.to_s
 
         begin
           @macos = if args.count > 1
             MacOSRequirement.new([args], comparator: "==")
-          elsif MacOSVersion::SYMBOLS.key?(args.first)
+          elsif first_arg.is_a?(Symbol) && MacOSVersion::SYMBOLS.key?(first_arg)
             MacOSRequirement.new([args.first], comparator: "==")
-          elsif (md = /^\s*(?<comparator><|>|[=<>]=)\s*:(?<version>\S+)\s*$/.match(first_arg))
+          elsif (md = /^\s*(?<comparator><|>|[=<>]=)\s*:(?<version>\S+)\s*$/.match(first_arg_s))
             MacOSRequirement.new([T.must(md[:version]).to_sym], comparator: md[:comparator])
-          elsif (md = /^\s*(?<comparator><|>|[=<>]=)\s*(?<version>\S+)\s*$/.match(first_arg))
+          elsif (md = /^\s*(?<comparator><|>|[=<>]=)\s*(?<version>\S+)\s*$/.match(first_arg_s))
             MacOSRequirement.new([md[:version]], comparator: md[:comparator])
           # This is not duplicate of the first case: see `args.first` and a different comparator.
           else # rubocop:disable Lint/DuplicateBranch
diff --git a/Library/Homebrew/macos_version.rb b/Library/Homebrew/macos_version.rb
index f71a2e6e73..6d1b8239ed 100644
--- a/Library/Homebrew/macos_version.rb
+++ b/Library/Homebrew/macos_version.rb
@@ -1,4 +1,4 @@
-# typed: true # rubocop:todo Sorbet/StrictSigil
+# typed: strong
 # frozen_string_literal: true
 
 require "version"
@@ -10,6 +10,7 @@ class MacOSVersion < Version
     sig { returns(T.nilable(T.any(String, Symbol))) }
     attr_reader :version
 
+    sig { params(version: T.nilable(T.any(String, Symbol))).void }
     def initialize(version)
       @version = version
       super "unknown or unsupported macOS version: #{version.inspect}"
@@ -18,7 +19,7 @@ class MacOSVersion < Version
 
   # NOTE: When removing symbols here, ensure that they are added
   #       to `DEPRECATED_MACOS_VERSIONS` in `MacOSRequirement`.
-  SYMBOLS = {
+  SYMBOLS = T.let({
     tahoe:       "26",
     sequoia:     "15",
     sonoma:      "14",
@@ -30,7 +31,7 @@ class MacOSVersion < Version
     high_sierra: "10.13",
     sierra:      "10.12",
     el_capitan:  "10.11",
-  }.freeze
+  }.freeze, T::Hash[Symbol, String])
 
   sig { params(macos_version: MacOSVersion).returns(Version) }
   def self.kernel_major_version(macos_version)
@@ -57,7 +58,9 @@ class MacOSVersion < Version
 
     super(T.must(version))
 
-    @comparison_cache = {}
+    @comparison_cache = T.let({}, T::Hash[T.untyped, T.nilable(Integer)])
+    @pretty_name = T.let(nil, T.nilable(String))
+    @sym = T.let(nil, T.nilable(Symbol))
   end
 
   sig { override.params(other: T.untyped).returns(T.nilable(Integer)) }
@@ -95,7 +98,7 @@ class MacOSVersion < Version
 
   sig { returns(Symbol) }
   def to_sym
-    return @sym if defined?(@sym)
+    return @sym if @sym
 
     sym = SYMBOLS.invert.fetch(strip_patch.to_s, :dunno)
 
@@ -106,7 +109,7 @@ class MacOSVersion < Version
 
   sig { returns(String) }
   def pretty_name
-    return @pretty_name if defined?(@pretty_name)
+    return @pretty_name if @pretty_name
 
     pretty_name = to_sym.to_s.split("_").map(&:capitalize).join(" ").freeze
 
@@ -154,5 +157,7 @@ class MacOSVersion < Version
   # Represents the absence of a version.
   #
   # NOTE: Constructor needs to called with an arbitrary macOS-like version which is then set to `nil`.
-  NULL = MacOSVersion.new("10.0").tap { |v| v.instance_variable_set(:@version, nil) }.freeze
+  NULL = T.let(MacOSVersion.new("10.0").tap do |v|
+    T.let(v, MacOSVersion).instance_variable_set(:@version, nil)
+  end.freeze, MacOSVersion)
 end
diff --git a/Library/Homebrew/test/macos_version_spec.rb b/Library/Homebrew/test/macos_version_spec.rb
index b6917f7797..706bcfc9a8 100644
--- a/Library/Homebrew/test/macos_version_spec.rb
+++ b/Library/Homebrew/test/macos_version_spec.rb
@@ -4,12 +4,15 @@ require "macos_version"
 
 RSpec.describe MacOSVersion do
   let(:version) { described_class.new("10.14") }
+  let(:tahoe_major) { described_class.new("26.0") }
   let(:big_sur_major) { described_class.new("11.0") }
   let(:big_sur_update) { described_class.new("11.1") }
+  let(:frozen_version) { described_class.new("10.14").freeze }
 
-  describe ".kernel_major_version" do
+  describe "::kernel_major_version" do
     it "returns the kernel major version" do
       expect(described_class.kernel_major_version(version)).to eq "18"
+      expect(described_class.kernel_major_version(tahoe_major)).to eq "25"
       expect(described_class.kernel_major_version(big_sur_major)).to eq "20"
       expect(described_class.kernel_major_version(big_sur_update)).to eq "20"
     end
@@ -19,12 +22,43 @@ RSpec.describe MacOSVersion do
     end
   end
 
+  describe "::from_symbol" do
+    it "raises an error if the symbol is not a valid macOS version" do
+      expect do
+        described_class.from_symbol(:foo)
+      end.to raise_error(MacOSVersion::Error, "unknown or unsupported macOS version: :foo")
+    end
+
+    it "creates a new version from a valid macOS version" do
+      symbol_version = described_class.from_symbol(:mojave)
+      expect(symbol_version).to eq(version)
+    end
+  end
+
+  describe "#new" do
+    it "raises an error if the version is not a valid macOS version" do
+      expect do
+        described_class.new("1.2")
+      end.to raise_error(MacOSVersion::Error, 'unknown or unsupported macOS version: "1.2"')
+    end
+
+    it "creates a new version from a valid macOS version" do
+      string_version = described_class.new("11")
+      expect(string_version).to eq(:big_sur)
+    end
+  end
+
   specify "comparison with Symbol" do
     expect(version).to be > :high_sierra
     expect(version).to eq :mojave
     # We're explicitly testing the `===` operator results here.
     expect(version).to be === :mojave # rubocop:disable Style/CaseEquality
     expect(version).to be < :catalina
+
+    # This should work like a normal comparison but the result won't be added
+    # to the `@comparison_cache` hash because the object is frozen.
+    expect(frozen_version).to eq :mojave
+    expect(frozen_version.instance_variable_get(:@comparison_cache)).to eq({})
   end
 
   specify "comparison with Integer" do
@@ -64,44 +98,90 @@ RSpec.describe MacOSVersion do
     end
   end
 
-  describe "#new" do
-    it "raises an error if the version is not a valid macOS version" do
-      expect do
-        described_class.new("1.2")
-      end.to raise_error(MacOSVersion::Error, 'unknown or unsupported macOS version: "1.2"')
+  describe "#strip_patch" do
+    let(:catalina_update) { described_class.new("10.15.1") }
+
+    it "returns the version without the patch" do
+      expect(big_sur_update.strip_patch).to eq(described_class.new("11"))
+      expect(catalina_update.strip_patch).to eq(described_class.new("10.15"))
     end
 
-    it "creates a new version from a valid macOS version" do
-      string_version = described_class.new("11")
-      expect(string_version).to eq(:big_sur)
+    it "returns self if version is null" do
+      expect(described_class::NULL.strip_patch).to be described_class::NULL
     end
   end
 
-  describe "#from_symbol" do
-    it "raises an error if the symbol is not a valid macOS version" do
-      expect do
-        described_class.from_symbol(:foo)
-      end.to raise_error(MacOSVersion::Error, "unknown or unsupported macOS version: :foo")
-    end
+  specify "#to_sym" do
+    version_symbol = :mojave
 
-    it "creates a new version from a valid macOS version" do
-      symbol_version = described_class.from_symbol(:mojave)
-      expect(symbol_version).to eq(version)
-    end
+    # We call this more than once to exercise the caching logic
+    expect(version.to_sym).to eq(version_symbol)
+    expect(version.to_sym).to eq(version_symbol)
+
+    # This should work like a normal but the symbol won't be stored as the
+    # `@sym` instance variable because the object is frozen.
+    expect(frozen_version.to_sym).to eq(version_symbol)
+    expect(frozen_version.instance_variable_get(:@sym)).to be_nil
+
+    expect(described_class::NULL.to_sym).to eq(:dunno)
   end
 
   specify "#pretty_name" do
+    version_pretty_name = "Mojave"
+
     expect(described_class.new("10.11").pretty_name).to eq("El Capitan")
-    expect(described_class.new("10.14").pretty_name).to eq("Mojave")
+
+    # We call this more than once to exercise the caching logic
+    expect(version.pretty_name).to eq(version_pretty_name)
+    expect(version.pretty_name).to eq(version_pretty_name)
+
+    # This should work like a normal but the computed name won't be stored as
+    # the `@pretty_name` instance variable because the object is frozen.
+    expect(frozen_version.pretty_name).to eq(version_pretty_name)
+    expect(frozen_version.instance_variable_get(:@pretty_name)).to be_nil
   end
 
   specify "#inspect" do
     expect(described_class.new("11").inspect).to eq("#<MacOSVersion: \"11\">")
   end
 
-  specify "#requires_nehalem_cpu?", :needs_macos do
-    expect(Hardware::CPU).to receive(:type).at_least(:twice).and_return(:intel)
-    expect(described_class.new("10.14").requires_nehalem_cpu?).to be true
-    expect(described_class.new("10.12").requires_nehalem_cpu?).to be false
+  specify "#outdated_release?" do
+    expect(described_class.new(described_class::SYMBOLS.values.first).outdated_release?).to be false
+    expect(described_class.new("10.0").outdated_release?).to be true
+  end
+
+  specify "#prerelease?" do
+    expect(described_class.new("1000").prerelease?).to be true
+  end
+
+  specify "#unsupported_release?" do
+    expect(described_class.new("10.0").unsupported_release?).to be true
+    expect(described_class.new("1000").prerelease?).to be true
+  end
+
+  describe "#requires_nehalem_cpu?", :needs_macos do
+    context "when CPU is Intel" do
+      it "returns true if version requires a Nehalem CPU" do
+        allow(Hardware::CPU).to receive(:type).and_return(:intel)
+        expect(described_class.new("10.14").requires_nehalem_cpu?).to be true
+      end
+
+      it "returns false if version does not require a Nehalem CPU" do
+        allow(Hardware::CPU).to receive(:type).and_return(:intel)
+        expect(described_class.new("10.12").requires_nehalem_cpu?).to be false
+      end
+    end
+
+    context "when CPU is not Intel" do
+      it "raises an error" do
+        allow(Hardware::CPU).to receive(:type).and_return(:arm)
+        expect { described_class.new("10.14").requires_nehalem_cpu? }
+          .to raise_error(ArgumentError)
+      end
+    end
+
+    it "returns false when version is null" do
+      expect(described_class::NULL.requires_nehalem_cpu?).to be false
+    end
   end
 end