I've just switched my 5G phone to LTE. LTE seems more reliable. I was at one of my frequent spots and had lots of 5G bars... can't connect to anything. Switched to LTE, works fine.
Wifey has the same issue on her T Mo iphone 12. While I'm sure that location has a lot to do with it, I wonder if 5g is just not ready yet for prime time in some areas? I've held off upgrading from my hand me down Samsung Note 9 to a Samsung S21 because of all the reports that 5g just depletes battery life and isn't that much faster than LTE in our area. Looking forward to the day when I can download a movie in mere seconds!