Brightness/Dimming Issue

My new iPhone 12 Mini’s screen brightness dims as the phone heats. The more it heats the more it dims, but unfortunately my phone heats up rather quickly (even as I type now it keeps dimming lower and lower, with nothing else running in the background.) I’ve contacted Apple support several times and even went into their Genius Bar in person to get the phone looked at but in their diagnosis report everything turned out fine, they found no problem. I’ve done this in person, over the phone, through text support and it always results in the same thing, being told my phone is working as intended and that everything is fine. I guess my question is will there be a fix or resolution or should I just lose hope in Apple and move over to something else, has anyone been successful in getting help with this issue?