Unfortunately, this is not true. I also thought it was something to do with ProMotion, but it's not. You can go into the accessibility options and disable ProMotion and it will still happen after several hours.
This is not the case though: you literally cannot disable ProMotion, it's impossible to do so. Limiting the frame rate to 60 HZ only limits ProMotion's range of movement to 1-60 or 10-60 rather than 1-120 or 10-120, it doesn't switch it off.
And fwiw, yep, totally agree that this is an absolutely humongous issue on iPhone 14 PM and on the M2 iPad as well.
I have 2 M2 iPads and games are unplayable on them, they stutter a hundred times worse than M1 ever did before OS 16 came out. You can see that it is ProMotion in this case because the stutter lessens a little bit when limiting to 60 HZ, and evaporates entirely when you put Screen Recording on which forces a constant 120 HZ (but this is not a solution because we can't just record everything we do and overheat the device just to make it run how it's supposed to to begin with).