iPhone 12 pro max keeps dimming

So.. I had my apple appointment yesterday, I made sure to video the screen dimming too before I went in, I showed them the videos and explained the issue I was having, to which they admitted was very strange, they said it’s most like software based to which I agreed, but i said, what are you going to do about it, to which they responded, there’s nothing we can do, other than try a screen replacement, so I said go ahead. Now, to do the screen replacement they have to plug the device into a diagnostic machine which will look for a fault and then allow them to do a repair, so they did this, and to both mine and the employees surprised, there were 5 faults with the device! It failed the screen test, the face I.D test, ambient lighting test and two other which I forget, but this meant that they couldn’t do a screen replacement as there were many more issues, so their solution… they straight up replaced my device there and then in the shop! I was gob smacked at this point as usual you’d hear horror stories of how they will blame you and send you away! So far it’s been 24hrs, no screen dim! I’ve even done the things I did before to make it happen, and nothing! So for now, I am happy, I hope this device continues to perform correctly and if I do experience any issues I will be sure to note them here!

my advise, video your issue on another device and head to your nearest apple store!