Seems this was fixed with the patch as well as there was no answer.
Going to mark this as fixed for now but leave open for a moment longer.
Please post if you still newly have this on a vanilla game.
This happened to me on PC as well, and I have a feeling I know exactly what is happening.
All of the pre-made sims have localization keys associated with their names. For whatever reason (my hunch is new localization entries), when you load a save made prior to the July 20th patch after applying the patch, it reads the names from the localization keys, rather than the save file. As far as my experience goes, it doesn't change household names, just the names of sims.
If you edit all the names back to what they were in the old save and save the game, the edited names remain on reload, so it's just an issue with loading saves made prior to the patch.
@DainKinkaideNot for me. I created a new game save today too test this & downloaded a gallery household uploaded July 2020. Gladstone Gander was created from Sergio Romeo of Windenburg. On the gallery his name is Gladstone. But when added to CAS his name reverts to Sergio Romeo.
https://drive.google.com/file/d/1nw5DSQWsphL4ZyKv2bS90P5RmYASoHAJ/view?usp=drivesdk
https://drive.google.com/file/d/1nq-OaXSEoD1iSDRf93xNYZONIVcguUAN/view?usp=drivesdk
This happens on PC & PS4
