Having bars doesn't necessarily mean calls can be made or received. Mine keeps fluctuating between 0 and 5 bars but wherever I try to make a call, it claims I'm not registered with my current carrier, which uses AT&T as its backbone.
That's something I've noticed in general with 5G - basically five bars means you've got a good connection to the tower, but you could have bad service due to a bottleneck upstream of that. (At least for data - for voice that might be more negligible.)
That’s been an issue for a lot longer than that, at least in dense metro areas. Even back in the 3G days I’d have 5 bars and no data due to tower congestion.
