This definitely sounds like abnormal behaviour, and something you should contact support over.
I dare say there will be wildly differing responses here. But I’d guess, like many others, I’ve had no issue so far.
Since day 1, I’ve had 5G Auto enabled, and neither heat, nor battery drain have been an issue. In fact, with my 12PM, I have yet to get to the end of a day with even a low battery warning.
My 11PM could sometimes get me through a day, though I’d normally need a little top-up in the afternoon. Of course this battery is brand new, but I’ve still been stunned that it’s had so much left to spare, considering it’s got a slightly smaller battery than my 11PM. It’s one aspect I’ve been very impressed by.