I'm using an unlocked Edge on AT&T with no problems. I get that 5Ge icon but no real 5G. I don't believe AT&T supports 5G on this phone, or ar least on the unlocked version. I had the dreaded screen issue with my first Edge, but Moto replaced it quickly and my second one has been perfect.
Just activated a Motorola Think Phone on AT&T... and it took several days before the 5G became stable. It was all over the place at first. But now the 5G - which is fairly new here in central IL- never leaves the phone. How is it now?