my iphone 13 pro manages the 4g+ bands poorly, because it insists on staying connected on a band with a low signal strength instead of moving to another one that has a better signal. for example, band 3 indoors has a poor signal, and band 20 has a very good signal. Well, indoors it is still connected to 3, instead of going to 20, and I have 1 or 2 lines of coverage, when with 20 I have full coverage.
I've talked to both apple and the carrier to see if they can fix it, but neither seem interested in doing so.