@porkypine90 First of all, you're going to need to use the EA App to launch Sims 3, that is unless you own disc copies of the base game and all your packs, or you own the content in Steam. If you've installed via Origin or the EA App, the EA App will have to be running.
Additionally, please keep limiting Sims 3 (TS3.exe) to one CPU core while you're testing—this is the most reliable way, if also the most inconvenient, to get around the Alder Lake problem. If you'd prefer another approach, please wait until the game is working to switch methods.
For the issue itself, please set exceptions in your antivirus for TS3.exe and EADesktop.exe. If you only use Windows Defender, check whether Controlled Folder Access is enabled. If it is running, either disable it or set those same exceptions.
If this doesn't help, create a new admin Windows account and try playing in that. Make it local, as in, don't sign into Microsoft, and don't sync with any other services you normally use. You'll be able to (try to) launch Sims 3 without reinstalling anything.
