Thanks Quinn: Restructuring a large app is extremely painful process and expensive. Apple needs to do a better job of preventing these kind of bugs in the future. There should be unit tests and better code coverage on the linker.

Right it appears to be related to changes in the linker (ld64) that is causing the problem. I think huge number cocoa pods seems to overwhelm the linker in Xcode 13.3, but it is fine in Xcode 13.2.1.

Yes, this happens in iOS 14.