I just upgraded my AT&T data plan to the 5G last week. Only got it working on my N20U today after working with AT&T chat because it looks like I needed a newer SIM. Before it would only show 5Ge where my daughters 12 Pro was showing 5G so worked with AT&T to get it sorted out.
After that I got a chance to do a couple of speed tests near a few MMWave mini towers installed recently outside my neighborhood and a bit confused after my tests...
Below is a shot of the mini towers installed down my street. A couple of towers about 1000 feet apart and a couple of more a mile down and those two are also a couple 1000 feet apart.
The confusing part... When I am running a test maybe 100 feet away from a tower from my car... the display shows 5Ge and NOT 5G.

And when I run tests right next to them, I'm hitting 300+ Mbps every time.
I drive away and I'll go into areas where it just says 5G only. But I run a test and they are terrible... 27-50... < 75 Mbps range.

But I go back to those towers, phone changes to say 5Ge, run a couple of speed tests, and get 300+ Mbps.
Is Millimeter Wave 5G for AT&T suppose to show 5Ge on the phone?? I think one of the AT&T techs I spoke to (took a few to get my issue fixed) actually told me if I saw 5Ge in some areas it could be actually 5G but I kinda blew that off thinking he was just trying to get me off the phone. Is MMWave 5G a mix using 4G and that's why the odd display??
Just an interesting find my first day with 5G.
At home it always showed 5Ge until today after the new SIM. Now it shows 5G but not impressed with the "5G" only speeds from home. :-\
BTW... this is all happening in North Fort Lauderdale, FL area for those that was wondering.