"xattr -C <path/to/app.app>" is not a valid command

[TurtleHead-1]

-C (capital C) is not a valid tag for the macOS xattr command. the correct command that worked for me (on intel based mac, I don't know of apple silicon is different) was xattr -cr "path/to/app.app".

[Very-cool-guy]

apple silicon uses -cr too