iPhone 11 Pro Max overheating

While using Safari, my iPhone 11 has been heating up underneath the camera. And not just warm, it feels hot. I have about 6 tabs open in Safari at a time, not sure if that makes a difference. I’ve sent my phone into Apple, they did a restore and reset and a month later the same issue happened. This past Sunday it was so hot I took it to a local Apple repair store and had a technician look at it, of course he said the same thing. There weren’t any temperature issues logged so he restored the phone and that’s all he can do. Since my iPhone 11 was getting checked out I have been using my iPhone 8 Plus with the same backup from my 11, same issue is now happening on my iPhone 8. The most annoying part of it is my battery drains really fast while it’s overheating. So, now I constantly have to have a charger on me. Could this be an issue with something in my backup?