If you're playing Oblivion Remastered via the Microsoft Store, perhaps because you got it with your PC Game Pass subscription, then you have access to a patch that other players do not. But before Steam users get jealous, this is not a patch anyone would want.
This 2GB update seems like it was rolled out due to an issue with cross-play. If you loaded your PC save on an Xbox, it would bring over your resolution settings as well, making the suped-up Cyrodiil look wonky on your TV. However, the hotfix has completely removed upscaling options like DLSS and frame generation from the options menu for anyone who downloaded Oblivion Remastered from the Windows/Xbox Store.
And those options are pretty important. While it's [[link]] easy to get [[link]] a decent framerate in the sewer tutorial, once you step out into Oblivion's open world you'll pay a tax of maybe 30 frames per second just for the privilege of standing outdoors, even with ray-tracing turned off. Frame generation goes from an optional extra to an essential one even with a decent rig.
Bethesda's Community Manager to complaints, saying the hotfix "was for a few backend tweaks and nothing directly impacting game play, but we've seen it's affected some Microsoft Store players' UI settings for graphical settings." Not to worry though, as "Any graphic settings adjusted prior to the Microsoft Store hotfix, are still enabled and function normally."
Only users are reporting that's not the case. Follow the replies to that comment and you'll see plenty of players reporting that DLSS and FSR have been turned off, and frame generation too. Some are also reporting their settings dropped from Ultra to High without warning.
"The team is taking a look and working out a resolution," Bethesda's community manager concludes, "we will share more [[link]] info as soon as we can." Expect a hotfix for this hotfix early in the week, but if you set aside this weekend to barrel through the Thieves Guild questline via Game Pass, you have my sympathies.