I am giving you my opinion based on what i have seen and feel with my eyes. Because I've already had hardware problems with apple. I remember the issue with 4s battery when it came out. I was lasting less than 4 hours. Apple came out with many tests from phone support, ios updates and tried to say it was ok. Someone maybe settled down, I went through the problem and at last apple changed my 4s. The swap unit was 100% perfect.
From my point of view, I want to change the device with a new one. I will be refunded by amazon within the 19th of January, then i will order another device and I will let you know.
You can keep living with the hope of a software fix (that i'm sure will never come)being stuck with your convinction about the software issue. I wanna try with a new phone, 'cause I've seen with my eyes many many iphone 12 (friends and family) that are smooth and perfect. Hefr only mine have problems and it really doesn't mean other people uses the device better than me.
it's your money, you can borrow it with your convinction. I won't.
I first want to try, i have the rights to have a 100% working device. After that i'm ready to keep my device and wait for some magic software update. Or maybe give back the second unit and as it happened with antenna gate of iphone 4, wait for the iphone 12S.