Split out from #183474; see that issue for additional context. Capturing the important part here:

The local override for all the macOS projects appears to be broken. It's showing up as ../../{darwin/macos}/plugin_name just as on iOS, but the correct path would start with ../../../. It looks like the difference is that in iOS projects the Flutter group in the project is incorrectly example/ios rather than example/ios/Flutter. All the group-relative paths of the files in the iOS project are adjusting for that by having one less level of climbing the directory tree, but the same thing doesn't work on macOS.