diff --git a/Library/Homebrew/cmd/update-report.rb b/Library/Homebrew/cmd/update-report.rb
index aa5fb7efea..a061ddbff8 100644
--- a/Library/Homebrew/cmd/update-report.rb
+++ b/Library/Homebrew/cmd/update-report.rb
@@ -331,9 +331,6 @@ class Reporter
 
       if paths.any? { |p| tap.cask_file?(p) }
         case status
-        when "A"
-          # Have a dedicated report array for new casks.
-          @report[:AC] << tap.formula_file_to_name(src)
         when "D"
           # Have a dedicated report array for deleted casks.
           @report[:DC] << tap.formula_file_to_name(src)
@@ -413,12 +410,14 @@ class Reporter
       renamed_formulae << [old_full_name, new_full_name]
     end
 
-    unless renamed_formulae.empty?
+    if renamed_formulae.present?
       @report[:A] -= renamed_formulae.map(&:last)
       @report[:D] -= renamed_formulae.map(&:first)
-      @report[:R] = renamed_formulae.to_a
     end
 
+    # Only needed additions for calculating deletions correctly based on renames.
+    @report.delete(:A)
+
     @report
   end
 
@@ -569,18 +568,18 @@ class ReporterHub
   delegate empty?: :@hash
 
   def dump(updated_formula_report: true)
-    # Key Legend: Added (A), Copied (C), Deleted (D), Modified (M), Renamed (R)
+    if ENV["HOMEBREW_UPDATE_REPORT_ONLY_INSTALLED"]
+      opoo "HOMEBREW_UPDATE_REPORT_ONLY_INSTALLED can be unset, it is now the default!"
+    end
 
-    dump_formula_report :A, "New Formulae"
+    # Key Legend: Added (A), Copied (C), Deleted (D), Modified (M), Renamed (R)
     if updated_formula_report
       dump_formula_report :M, "Updated Formulae"
     else
       updated = select_formula(:M).count
       ohai "Updated Formulae", "Updated #{updated} #{"formula".pluralize(updated)}." if updated.positive?
     end
-    dump_formula_report :R, "Renamed Formulae"
     dump_formula_report :D, "Deleted Formulae"
-    dump_formula_report :AC, "New Casks"
     if updated_formula_report
       dump_formula_report :MC, "Updated Casks"
     else
@@ -593,33 +592,13 @@ class ReporterHub
   private
 
   def dump_formula_report(key, title)
-    # TODO: 3.4.0: odisabled the old functionality and make this default
-    only_installed = Homebrew::EnvConfig.update_report_only_installed?
-
-    formulae = select_formula(key).sort.map do |name, new_name|
-      # Format list items of renamed formulae
+    formulae = select_formula(key).sort.map do |name, _new_name|
       case key
-      when :R
-        name = pretty_installed(name) if installed?(name)
-        new_name = pretty_installed(new_name) if installed?(new_name)
-        "#{name} -> #{new_name}" unless only_installed
-      when :A
-        name if !installed?(name) && !only_installed
-      when :AC
-        name.split("/").last if !cask_installed?(name) && !only_installed
       when :MC, :DC
         name = name.split("/").last
-        if cask_installed?(name)
-          pretty_installed(name)
-        elsif !only_installed
-          name
-        end
-      else
-        if installed?(name)
-          pretty_installed(name)
-        elsif !only_installed
-          name
-        end
+        pretty_installed(name) if cask_installed?(name)
+      when :M, :D
+        pretty_installed(name) if installed?(name)
       end
     end.compact
 
diff --git a/Library/Homebrew/env_config.rb b/Library/Homebrew/env_config.rb
index 08728a43ae..daf7c41eb7 100644
--- a/Library/Homebrew/env_config.rb
+++ b/Library/Homebrew/env_config.rb
@@ -325,10 +325,6 @@ module Homebrew
         default_text: "macOS: `/private/tmp`, Linux: `/tmp`.",
         default:      HOMEBREW_DEFAULT_TEMP,
       },
-      HOMEBREW_UPDATE_REPORT_ONLY_INSTALLED:     {
-        description: "If set, `brew update` only lists updates to installed software.",
-        boolean:     true,
-      },
       HOMEBREW_UPDATE_TO_TAG:                    {
         description: "If set, always use the latest stable tag (even if developer commands " \
                      "have been run).",
diff --git a/Library/Homebrew/sorbet/rbi/hidden-definitions/hidden.rbi b/Library/Homebrew/sorbet/rbi/hidden-definitions/hidden.rbi
index 268f8a2953..90fca4a6b2 100644
--- a/Library/Homebrew/sorbet/rbi/hidden-definitions/hidden.rbi
+++ b/Library/Homebrew/sorbet/rbi/hidden-definitions/hidden.rbi
@@ -2626,8 +2626,6 @@ module Homebrew::EnvConfig
 
   def self.temp(); end
 
-  def self.update_report_only_installed?(); end
-
   def self.update_to_tag?(); end
 
   def self.verbose?(); end
diff --git a/Library/Homebrew/test/cmd/update-report_spec.rb b/Library/Homebrew/test/cmd/update-report_spec.rb
index c31b6e32ec..34657525c3 100644
--- a/Library/Homebrew/test/cmd/update-report_spec.rb
+++ b/Library/Homebrew/test/cmd/update-report_spec.rb
@@ -53,7 +53,6 @@ describe "brew update-report" do
       perform_update("update_git_diff_output_without_formulae_changes")
 
       expect(hub.select_formula(:M)).to be_empty
-      expect(hub.select_formula(:A)).to be_empty
       expect(hub.select_formula(:D)).to be_empty
     end
 
@@ -61,7 +60,6 @@ describe "brew update-report" do
       perform_update("update_git_diff_output_with_formulae_changes")
 
       expect(hub.select_formula(:M)).to eq(%w[xar yajl])
-      expect(hub.select_formula(:A)).to eq(%w[antiword bash-completion ddrescue dict lua])
     end
 
     specify "with removed Formulae" do
@@ -74,7 +72,6 @@ describe "brew update-report" do
       perform_update("update_git_diff_output_with_changed_filetype")
 
       expect(hub.select_formula(:M)).to eq(%w[elixir])
-      expect(hub.select_formula(:A)).to eq(%w[libbson])
       expect(hub.select_formula(:D)).to eq(%w[libgsasl])
     end
 
@@ -82,9 +79,7 @@ describe "brew update-report" do
       allow(tap).to receive(:formula_renames).and_return("cv" => "progress")
       perform_update("update_git_diff_output_with_formula_rename")
 
-      expect(hub.select_formula(:A)).to be_empty
       expect(hub.select_formula(:D)).to be_empty
-      expect(hub.select_formula(:R)).to eq([["cv", "progress"]])
     end
 
     context "when updating a Tap other than the core Tap" do
@@ -101,32 +96,25 @@ describe "brew update-report" do
       specify "with restructured Tap" do
         perform_update("update_git_diff_output_with_restructured_tap")
 
-        expect(hub.select_formula(:A)).to be_empty
         expect(hub.select_formula(:D)).to be_empty
-        expect(hub.select_formula(:R)).to be_empty
       end
 
       specify "with renamed Formula and restructured Tap" do
         allow(tap).to receive(:formula_renames).and_return("xchat" => "xchat2")
         perform_update("update_git_diff_output_with_formula_rename_and_restructuring")
 
-        expect(hub.select_formula(:A)).to be_empty
         expect(hub.select_formula(:D)).to be_empty
-        expect(hub.select_formula(:R)).to eq([%w[foo/bar/xchat foo/bar/xchat2]])
       end
 
       specify "with simulated 'homebrew/php' restructuring" do
         perform_update("update_git_diff_simulate_homebrew_php_restructuring")
 
-        expect(hub.select_formula(:A)).to be_empty
         expect(hub.select_formula(:D)).to be_empty
-        expect(hub.select_formula(:R)).to be_empty
       end
 
       specify "with Formula changes" do
         perform_update("update_git_diff_output_with_tap_formulae_changes")
 
-        expect(hub.select_formula(:A)).to eq(%w[foo/bar/lua])
         expect(hub.select_formula(:M)).to eq(%w[foo/bar/git])
         expect(hub.select_formula(:D)).to be_empty
       end