You’ve probably tried this but in case you haven’t: try putting isopropyl alcohol in the gaps around the bumpers, it can clean the contacts and make the bumpers work again.

But yeah I’ve also has a ton of first party xbox controllers fail on me, although usually its the left stick or right trigger (I mostly play rocket league which abuses both) and was mostly the xbox one controllers so I’ve switched to more durable 3rd party controllers.

My experience is they’re roughly as polite as Parisians

PCIe scaling isn’t really significant. With a 4090 you lose 2% going to 3.0 instead of 4.0 at 1440p per techpowerup https://www.techpowerup.com/review/nvidia-geforce-rtx-4090-pci-express-scaling/28.html

He is using and instead of nvidia and linux instead of windows but his card is so much slower that the drop should be a lot less

From some other benches people have posted, ultra settings at 1440p he should be averaging 180 fps then even if he is using 3.0 x4 due to lane splitting from ssds which is roughly equivalent to pcie 1.1 x16 then it’s probably still not the main culprit