I should note that some frameworks may not contain a resource like a privacy manifest, but it's being observed here that Xcode doesn't seem to care and will embed anyway. I expect it does the embedding by default since it would be difficult to programmatically determine whether a static framework contains resources the developer wants copied in or not.

The Firebase SDKs are receiving reports about this issue. I tried replacing the LSMinimumSystemVersion with 11.0, deleting derived data, and rebuilding. I still reproduced the same error that referred to 10.15 (despite the macCatalyst slice's plist not containing it). It looks like the workaround is to use 15.3 for now.