The clue of "an hour of gaming" tells me it's heat or the game. To figure that out I remove desktop case cover and point a small fan at the open case. Then test.
If it's heat that issue will occur later than one hour. If it remains the same then it is likely some game or configuration issue (it does not tell us which.)
But the story is in line with heat buildup.
So for the past couple of months, my mouse has been acting weirdly and no one seems to have had this problem on forums. When I start my computer everything works fine but after maybe like an hour of gaming my mouse start to have a very slow response time. It's really weird to explain, but it feels weird. My aim is not as crispy and fast. The best comparison I can make is that it feels like it has a low frame rate. Compare it to a monitor, 120 fps vs 10 fps. Everything takes more time to react and feels buggy. That's exactly how my aim feels like. I've looked everywhere on the internet but couldn't find a fix to this problem, so here I am asking for help haha. Thank you for your time!
Specs : Processor : Intel(R) Core(TM) i3-8100 CPU @ 3.60 GHz (4GB VRAM)
Graphics Card : GeForce GTX 1050 Ti
TV : HKC TV 60Hz
Mouse : Corsair Harpoon RGB Wireless