I noticed iCloud private relay doesn’t relay traceroute packets either but does relay some https traffic. I think perhaps it should be called alpha? Seems completely unpredictable

Oops. So currently there’s no way to delete an answer that was meant to be a comment?

Realized I didn’t specify that I was trying with popular presumably relatively bug free apps when I wrote “For every app I tried, I got an error like” Not ones I had built. So yes they had the Info plist files. I never did figure this out, but forgot to come back here.

Private Relay targets the shuffling of IP addresses of HTTPS-related protocols I’m curious what you mean by that. (That’s not something I’ve heard of. )

Eaton’s provided some helpful info here but it does seem to confirm the issue: https://developer.apple.com/forums/thread/683957

No one can help you without more info on what you have , tried...