Strange spots on the characters' skin

@H3AVY_GRG  Do you see these spots anywhere else in the game?  Are you using custom skins, and if so, did you try without them?

Additionally, do you have a different graphics card you could test with?  Even if you need to borrow one from a friend or family member, it would be useful to know whether this problem showed up with a different GPU installed.  Your processor doesn't have integrated graphics, so you'd need a discrete card.

I haven't seen enough examples of people playing Sims 3 on an Intel Arc card to know whether this is normal, or at least a common issue.

Please also run a dxdiag and attach it to a post.

https://help.ea.com/en-us/help/pc/how-to-gather-dxdiag-information/

Funny you ask, as I have a RX5700 XT that I couldn't sell. When I have time, I'll swap the video cards and check it out

No, no mods, just a patch for the video cards.

dxdiag file will be attached to the message

@H3AVY_GRG  I'll be curious to know whether the 5700XT is affected too, although I would guess not.  Additionally, it's worth repairing Sims 3 to undo the effect of the patch you ran.  That patch may be fine, but it's also an easy test.  In the EA App, repair is under Sims 3 > Manage; in Steam, it's Properties > Local files > Verify integrity of the game files.

The errors in your dxdiag are all from Adobe Acrobat Reader, so you may need to force an update, or uninstall and reinstall entirely.  It would be odd for these errors to have any influence on Sims 3, but at the very least, please make sure all Adobe-related processes are closed before playing, even those that might be running in the background.

Your C drive is also very low on free storage, enough that you might see strange behavior both from games and from Windows itself.  Since D and E both have plenty of free space, it should be simple enough to move some data around.