XCode 12, FIRAnalyticsConnector, Build Error

Ok, I finally found a fix for the issue.

Change "Build Active Architecture Only" to "Yes" also for "Release".
The setting can be found selecting your project > "Build Settings" > "Targets" (your target) > "Architectures"

Source and more elaborate explanation can be found here:
https://stackoverflow.com/a/64139830/4134160

Please note that the problem is not related to Firebase. I'll still leave it since it might lead others to this issue and help them to resolve this.

My case was a little different. According to this Firebase engineer,

FIRAnalyticsConnector is now part of the xcframework version of FirebaseAnalytics and isn't needed to link.

Going into the Targets Build Settings (not the Project), searching for Other Linker Flags, and then deleting FIRAnalyticsConnector from the list took care of the issue for me.

Interestingly, when I ran pod deintegrate and the pod install it did not fix this issue.

After adding "arm64" to Excluded Architectures for the project AND the pods, I was able to resolve this issue I ran into on an Apple M1.

I also had to clear DerivedData and restart XCode.

See: https://medium.com/@khushwanttanwar/xcode-12-compilation-errors-while-running-with-ios-14-simulators-5731c91326e9