Trying to get notarytool running on 10.15.7 with Xcode 12.4 here and I've run into an issue with a dylib: ~ % /Applications/Xcode12.app/Contents/Developer/usr/bin/notarytool dyld: Library not loaded: /usr/lib/swift/libswift_Concurrency.dylib

This SE post might be the answer, it immediately went away after running the specified command: sudo pmset schedule cancelall https://apple.stackexchange.com/questions/175361/powerd-process-uses-a-lot-of-cpu/444501#444501