Seeing as there were people reporting the issue on Beta 2 and 3, I suspect it's server side, not a bug in Beta 4. Could be that the Update Server has responded to automatic update pings from our devices saying that public release is out and they want everyone off the beta. Once that flag is set on our devices, it notifies us, and the longer we go, the more often it nags us, thus why some of us had it only happening once/twice a day until last night. Also explains why it's happening to people on Beta 2/3, as well as iPhone 12 users on 14.1.
Therefore, any fix would be on Apple's end, not an update sent to us.