We have metrics that show in 2024 Q1 less than 1% of flutter create apps were Objective-C. Deprecate and remove the flag and templates.

• IntelliJ Remove iOS languages from new project creation flutter-intellij#7439
• VS Code Remove --ios-language for Flutter > 3.22 and update setting description Dart-Code/Dart-Code#5145
• Support creation of add-to-app modules in Swift #23955
• Remove references to soon-to-be-deprecated "flutter create --ios-language" flag  website#11200
• Add a deprecation warning that the flag will be removed in a future release. Let that sit for a stable release or so to see if we get complaints. Add deprecation warning for "flutter create --ios-language" #155867
• Remove deprecated Objective-C iOS app create template #169547
• Recreate packages examples with the Swift template (see comment in totally unrelated issue about doing the same for kotlin Update settings.gradle for example apps to remove .flutter-plugins #157660 (comment))
• Optionally: recreate Objective-C sample, example apps with the Swift template

Users will still be able to open ios/Runner.xcworkspace and add Objective-C code or replace the Swift code that's there with Objective-C.

macOS never had a flutter create -i objc option and only provided a Swift template #70598 (comment)