But to be fair, phones are not built for longer 4K and 8K video recording.The iPhone 12 series got overheating problems too.Even the big DSLRs are heating up enormously and got some heat problems in heavy use.
Yes, I know my friend, i had many phones and I have DSLR. But this is "Overheat". I test 2 phone S21U and Note 10 Plus in the same room, with just opening camera application and wait 5 - 10 minutes, the Note 10 Plus is hot just 43 degrees but S21U cant reached 10 minutes, it forced close bu software and when you touch the phone it is very, very, very, hot. If I hold the Note 10 Plus, I even cant feel the hot. It is not the problem that phone go very hot the problem is you can use camera app.
If I use any other things in camera like video recording, slowmotionu, talking portrait photos and etc... it will go hot much more and much faster.
Please, if you dont believe me you have many post on Redit or Samsung official forum and many others.
I don't want to ruined this post on XDA. Just please if someone have the same problem and if the problem "go away" after some new update, please let me know. How I say I want to buy again but many of them is complaining about Overheating in camera an multitasking. And im scared to buy S21U because in my contry is very hard to return it.