I had the issue with xcodebuild & altool pipeline building iOS app while tvOS was fine. Build & upload iOS from Xcode IDE was fine as well. After @Luca_65 option --digest-algorithm=sha1,sha256 in OTHER_CODE_SIGN_FLAGS xcodebuild & altool iOS pipeline was fixed. macOS Catalina 10.15.7 Xcode 12.4

My Apple TV stopped to pair after upgrading to tvOS 15.6 with Xcode 13.4.1. Previously I was able to manage pairing with troubles. I have old router Asus RT-N66U. So, I tried to connect mac and tv to iPhone's hot spot and it paired just fine. It seems my old router is not so good for pairing. Try to use iPhone's hot spot. Maybe mac's ad-hoc network will work too. After that when Xcode fetched debug symbols for tvOS 15.6 over iPhone connection I connected mac and tv to router's network and pairing continued to work over router's wi-fi.