There Could be a lot of reasons why it heats, personally My Z Flip4 doesn't start heating up whenever I do any of the things you mentioned, however, the reason could be that you downloaded a lot of apps that take up a lot of space and GB and that could lead to heating issues, or maybe you don't clean up the memory weakly or take good care of your phone, I will give tips and things I do to prevent those things to happen and how I keep my phone working smoothly: 1. Do a device care daily (not necessarily but do it up to 3 times a week) 2. Uninstall excess or big apps that take up a lot of space. 3. Or you can put the apps that take a lot of space into deep sleep, i suggest this if you have any important apps. 4. Restart your phone at least once a week. 5. remove the apps that work in the background when you want to leave your phone.
It seems like a lot but believe me, it's worth it because your phone will start working smoothly 👌.
