Why downloads have to stop when we start playing something that needs internet connection

[Shiken]

It is like this for every console. I noticed on my Series X that the speed slows to 10 mbps (which may as well be stopped) just for having a game running, but as soon as I close it the speeds jump to 300-500 mbps. My PS4 Pro doesn't even let me use the full speed of my internet no matter what it is doing, and also goes even slower when playing online.

So this isn't isolated to Nintendo, and annoying no matter what platform it is on.