Finally could solve it by adding the right OS support manually in /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/

From Xcode assistance pages, I understand that this is "normal" Xcode 13.2.1 does not support iOS 15.4 :-((( You have to update to Xcode 13.3 and to do so, to Monterey (and loose apps compatibility, as far as I am concerned)

Same situation 15.4.1 / 11.6.5 /13.2.1/watch, same error