skytitan74 RDR2 is certainly demanding enough to put your GPU through its paces, lost save or not. So I don't know exactly what's going on here. I'd still suggest testing with another graphics card if and when you have the opportunity, if only because it's another useful bit of data.
In the interim, please DDU the driver again and install a slightly older one. You can find them here:
https://www.nvidia.com/en-us/drivers/
Enter your product details (or really anything in the family or close), and on the Results page, click View More Versions. You'll want a Game Ready (not Studio) Driver, and a version that's a few months old would be a good test.
I haven't seen any confirmed reports that any new-ish driver, including this one, is incompatible with Sims 4 in any way, but it's always possible that something about your system is not getting along with a combination of the newest driver and Sims 4. That's speculation too, but it's also an easy test.
Something else you can try is a clean uninstall and reinstall of both Sims 4 and the EA App. I wrote out how to do it in the solution of this thread, which is for a different issue, but the approach is the same:
[CURRENT ISSUE] Sims 4 DLC shows as installed, won't load in-game | EA Forums - 11831673