Thank you Quinn! If there's nothing I can do to fix it, I just take it as it is and calm down. :)

Thank you Quinn! Here is the the bug report number – FB9775763.

Where were my eyes?! You are absolutely right! Oh my God, I'm still impenetrably stupid! Thank you very much!

The issue has been fixed in macOS Sonoma 14.5 build 23F5074a

Yes, thank you, applying this macro to a protocol satisfies the compiler. Is there any way to make something like this work with protocol extensions as well?