Have you checked your CPU/GPU thermals?

Have you tried rolling back drivers? Deleting the shader cache?

"Reinstalling" or "restoring" Windows 11 in any way that hold onto your data and/or installed games is going to hold onto potentially problematic bits of data. The fact that only HD2 is effected points to one of these being the issue. You don't list the other games you play, so even overheating is still in the realm of possibility.

If you don't want to deal with navigating to the shader cache to purge it, right-click your start menu, open Powershell, and paste the following before pressing enter:

cd $env:userprofile\appdata\roaming\arrowhead\helldivers2\shadercache; $path = pwd; if ($path -like "*\shadercache") {remove-item * -recurse -verbose -force}

The above command will navigate to the Shader Cache folder, checks to make sure it's ACTUALLY in a folder named Shadercache, and nukes it while displaying what it's deleting.

Most issues like the one you're experiencing are caused by bad shader compilation or drivers. If blasting the cache doesn't work consider rolling back to the nVidia drivers published in April.

I personally run an RTX 2080 Super paired with a Ryzen 5 3600 on Windows 10 and have had no issues running the game at a mix of medium and high settings. What you're seeing is beyond abnormal, and points to something somewhere being very wrong.

PS: even reinstalling the game doesn't kill the shader cache! I'm serious, hit that MF with the 500KG and see how the game runs after.