New to unreal, found that unlit material work OK, they do not cause this problem, there is a a way to use the normal material and do not cause this problem?
Playing PC do not have this problem even on low hardware.
Since you didn’t bother writing which “mobile” you’re testing on nor its specs, my guess from the screenshots is that the character material is more complex than the wall/ground materials (it uses an albedo, roughness, and normal maps, and is also dynamically lit), so the closer the camera it is the more work the GPU has to do because it occupies more pixels on the screen.
This is the performance you would get on your device if all objects used a material with the same features as the character’s.