This was supposed to be addressed in iOS 14.0.1, and it was, but now according to a tweet by David Clarke, it looks like the problem is back albeit in a different form. According to Clarke, it seems that if you were to update the app that you’re using for your default browser or email, it would again reset your settings.
This seems rather annoying because there’s a higher chance that your app could be updated whether it be for new features or bug fixes, compared to you restarting your phone. The good news is that based on some of the comments on Clarke’s tweet, it seems that Apple is aware of this and apparently it has been fixed in iOS 14.2.
https://twitter.com/DCOneFourSeven/status/1318878038113816577
Apple just released iOS 14.1 so it is unclear when iOS 14.2 will be released. A rumor had previously suggested that the AirTags accessory could launch alongside the release of iOS 14.3 this November, but it seems a bit odd that Apple would release a major update back to back with so little time in between them.