It seems like this is an ongoing issue and its driving me insane as well! Here is so more context about others whom are experiencing the issue.

Sharing that I ran into the same issue, using IVPN on both devices, my Mac and iPhone. @patras's answer seems to have fixed it for me! I had to turn off the VPN on both iPhone and Mac in order for the device to properly register via USB, which seems odd to me since there's a direct connection.

2018 11” iPad Pro and I’m having the same issue here. I was able to DFU then restore to a backup of 14.6 but upon trying to reinstall iPad OS 15, I ran into the same exact issue. So for now I am leaving it on 14.6 in hopes the next beta release fixes this.

This would be a great scenario for unit testing. You can take a look here at the documentation on unit testing. I can’t link specific websites where you can also learn tons about unit testing and how it can benefit you, especially in the situation like above. Your unit tests would be pretty simple once you understand how to write them. You simply want to get today’s date Date() and compare it to another date variable you have set yourself.