1) Bad 5G modem
2) Bad 5G coverage comparing other phones
3) When you move out of WiFi - it will take like forever to switch to Mobile Data
4) When you leave 5G coverage (which happens often due to bad modem) it takes time to switch 4G data (this frustrates a lot during UPI payments)
5) Once you reach back to 5G coverage area, it will again take its sweet a$& time to switch to 5G data (not allowing to use 5G UL offer)
This is even seen in 35 to 40k phones like A55 (I am using one). Few of them are somewhat fixed to a very little extend via updates, except hardware limitations. For complaint (3) I changed one setting in "Dev Options" (Keep mobile data always ON during WiFi), which affects battery life a little.