My Note 20 Ultra has been rebooting itself nightly for about a week now. It only does it at night. I don't know if wireless charging is the issue as I charge it this way every night but it's getting really old waking up to notifications I needed that evening when I was sleeping. I have tried clearing the phone's cache. It didn't reboot the first night after being cleared but started up again the night after.
If that doesn't work you could also try cable charging for a night, the wireless charger may be overheating the phone causing it to shutdown and then restart once it cooled down. This could be caused by the phone case you have (assuming your using one) if it's very bulky it would be harder to charge wirelessly therefore generating more heat.
I thought about that as a possibly but it all started in the last week or so and the case is the same. However, if this change of battery charge level works I'm going to turn it off (the battery protection setting) and try charging wirelessly without the case it's in. See how that goes. I appreciate all the help and ideas.