@kawaiisizzie The video didn't attach to the PM, but I saw it in your uploaded videos, and... wow. Could you try lowering the graphics settings to the minimum let me know whether that makes a difference? Try it with Advanced Rendering on and off.
Please change the graphics settings at the Main Menu, then quit to desktop before loading a save; otherwise, you could see some strange graphics glitches, although not worse than what you're looking at now. By the way, if you did change the settings while a save was loaded, or you loaded a save afterwards without quitting to desktop first, please delete options.ini from the Sims 3 user folder and start from scratch.
The thing is, your particular graphics chip seems to be struggling more than most with running Sims 3, at least in Big Sur. There may be an issue with the driver for that chip, and since drivers are part of the operating system, there's not a lot you can do for a driver problem other than update the OS and hope it comes with a new driver. As it happens, there's a new update available now: you're on 11.1 from the version number in your deviceconfig, and 11.2 was released last week. So you could try updating and see whether it makes a difference. If you do update, another clean folder would be in order as well, just to be thorough.
The deviceconfig is fine as is, and I'd prefer the newest one anyway. You can also open it in TextEdit if you want to edit it, but as long as the info is intact, the format doesn't matter to me.
By the way, if you could upload the video to YouTube or a different filesharing site and link it, that would be helpful. There's kind of a trick to getting videos to play properly on this site, so while it's doable, it's not as convenient for people who aren't used to it. And I'd like to share this video with some EA people if possible.