High-bandwidth wireless data, even using the latest 5G technology, still literally requires ample bandwidth: wide enough radio frequency channel(s) over which to communicate. So far, two major US cellular providers (AT&T and T-Mobile) have allocated so little spectrum space to 5G, that 4G connections are still faster in almost every city tested. For example, on AT&T’s 4G network, phones can use up to seven radio bands simultaneously to increase speeds, but phones on 5G are still limited to a single 5MHz band.
Sounds like this is what empirical testing of AT&T and T-Mobile networks would have expected to find. Verizon’s 5G network isn’t showing this issue because they’re using only millimeter-wave spectrum and equipment, with the trade-off being scant availability because of its tiny usable cell area.