diff --git a/pub/lib/dependabot/pub/update_checker.rb b/pub/lib/dependabot/pub/update_checker.rb
index 1fecf6f04d..01539b0766 100644
--- a/pub/lib/dependabot/pub/update_checker.rb
+++ b/pub/lib/dependabot/pub/update_checker.rb
@@ -134,21 +134,8 @@ def resolve_requirements_update_strategy
           [nil, "widen_ranges", "bump_versions", "bump_versions_if_necessary"].include? requirements_update_strategy
 
         if requirements_update_strategy.nil?
-          # Check for a version field in the pubspec.yaml. If it is present
-          # we assume the package is a library, and the requirement update
-          # strategy is widening. Otherwise we assume it is an application, and
-          # go for "bump_versions".
-          pubspec = dependency_files.find { |d| d.name == "pubspec.yaml" }
-          begin
-            parsed_pubspec = YAML.safe_load(pubspec.content, aliases: false)
-          rescue ScriptError
-            return "bump_versions"
-          end
-          if parsed_pubspec["version"].nil? || parsed_pubspec["publish_to"] == "none"
-            "bump_versions"
-          else
-            "widen_ranges"
-          end
+          # If no explicit strategy is given, default to 'increase-if-necessary' (#4979).
+          "bump_versions_if_necessary"
         else
           requirements_update_strategy
         end
diff --git a/pub/spec/dependabot/pub/update_checker_spec.rb b/pub/spec/dependabot/pub/update_checker_spec.rb
index 65e7ebb58b..22df319a7f 100644
--- a/pub/spec/dependabot/pub/update_checker_spec.rb
+++ b/pub/spec/dependabot/pub/update_checker_spec.rb
@@ -122,7 +122,7 @@
             }],
             "previous_version" => "1.14.13",
             "requirements" => [{
-              file: "pubspec.yaml", groups: ["direct"], requirement: "^1.16.0", source: nil
+              file: "pubspec.yaml", groups: ["direct"], requirement: "^1.14.13", source: nil
             }],
             "version" => "1.16.0" }
         ]
@@ -142,7 +142,7 @@
                 # Dependabot lifts this from the original dependency.
                 "previous_version" => "0.0.0",
                 "requirements" => [{
-                  file: "pubspec.yaml", groups: ["direct"], requirement: "^1.16.0", source: nil
+                  file: "pubspec.yaml", groups: ["direct"], requirement: "^1.14.13", source: nil
                 }],
                 "version" => "1.16.0" }
             ]
@@ -269,42 +269,6 @@
             ]
           end
         end
-        context "app (version but publish_to: none)" do
-          let(:project) { "can_update_publish_to_none" }
-          it "can update" do
-            expect(can_update).to be_truthy
-            expect(updated_dependencies).to eq [
-              { "name" => "retry",
-                "package_manager" => "pub",
-                "previous_requirements" => [{
-                  file: "pubspec.yaml", groups: ["direct"], requirement: "^2.0.0", source: nil
-                }],
-                "previous_version" => "2.0.0",
-                "requirements" => [{
-                  file: "pubspec.yaml", groups: ["direct"], requirement: "^3.1.0", source: nil
-                }],
-                "version" => "3.1.0" }
-            ]
-          end
-        end
-        context "library (has version)" do
-          let(:project) { "can_update_library" }
-          it "can update" do
-            expect(can_update).to be_truthy
-            expect(updated_dependencies).to eq [
-              { "name" => "retry",
-                "package_manager" => "pub",
-                "previous_requirements" => [{
-                  file: "pubspec.yaml", groups: ["direct"], requirement: "^2.0.0", source: nil
-                }],
-                "previous_version" => "2.0.0",
-                "requirements" => [{
-                  file: "pubspec.yaml", groups: ["direct"], requirement: ">=2.0.0 <4.0.0", source: nil
-                }],
-                "version" => "3.1.0" }
-            ]
-          end
-        end
       end
       context "with bump_versions strategy" do
         let(:requirements_update_strategy) { "bump_versions" }