First of all, there is a difference between SIM1 and SIM2 slot. How each phone manufacturer set their SIM2 is anybody guesses.

My cousin kept complaining his S23U dropping out of 5G and connect to 4G instead. I showed my wife S23U okay je. Then he found out that his sim card is in SIM2 and my wife phone is in SIM1. After replacing his sim card in SIM1, he no longer faced this problem.