I’m having the same issue
It’s in an entertainment cabinet with three shelves and there’s no door so it’s open air
It’s been there for over two years. I find it odd since the environment hasn’t changed
It’s on the top shelf, by itself And not sitting on top of any other equipment
The device does not feel any hotter than normal and I have unplugged it and plugged it back in and that seems to fix it for a while
Do these devices have a life and do they need to be replaced periodically because I’ve had this Roku ultra probably four years now maybe a little less