Ipad air M2 heating issue

My ipad Air M2 never heats even the slightest while playing high end games but when I use apple notes for some time or reading pdf's from files for some time then it starts heating a lot..

What can be the problem

My ipad Air M2 never heats even the slightest while playing high end games but when I use apple notes for some time or reading pdf's from files for some time then it starts heating a lot..

What can be the problem