I have the same issue, please help us

Please help with that, I have the same issue!

also if app is pushed to TestFlight, it's not possible to install to device with ios15, I afraid it will not work on ios 15 if it's pushed to store

I have finally fixed this issue. It was because danish letter Ø in associated domains, I have removed it and now it works for ios 15. I will report ios 15 issue, such as ios15 cant handle domains which has these special chars, but it should be possible such as site domain can have it.