iPhone 11 Heating. Serious or not?

Hi I just got my iPhone 11 and sometimes just by browsing Instagram or watching a video on YouTube the back of the phone heats up a little, nothing crazy I’m not getting any heat warning it just get hot enough to feel it and if turn its off and then back on after a few minutes I’m good. I’ve read on some forums that it might be an iOS 13 problem and I wanted to get a better idea. Thanks in advance.