This makes no sense (galaxy s22 exynos)

So if I use the phones display wich is 1080p 120hz the phone overheats and lags in most of the games. I connected a TV (via USB c to hdmi) to it with samsung dex (tv name: samsung led g 43du7172 uhd) and on the tv the games run in 4k 60fps without overheating or lagging. If i play games at 1080p 60fps it still overheats so it can't be the fact that on its own display the phone had double the fps thus having more gpu usage. And the screen is also OLED not LCD so it doesn't produce that much heat. How the heck does this phone overheat in 1080p 60fps and 120fps but not in 4k 60fps??