I wonder if your Series S was defective? I completed Guardians Of The Galaxy on my Series S with no hiccups
I don't know? I never really thought of it like that, I was always in the mind of, it's a software bug either in the game or the series S firmware that addresses the memory allocation for games and O/S, should be an easy fix with a firmware update if Xbox find an issue in the firmware or driver, so I don't think it's anything to really worry about but who knows.
I would be more concerned on the wear limit of a 500 gig ssd if people have to keep moving and reinstalling games from internal drive to external drive or even delete and install new games, makes me wonder what tech and wear limits the xbox series S Nand uses?
From what little I could find out about the series S SSD it didn't look good on the wear limit side of things but I had no way to confirm if the info was correct? But saying that I think the Xbox upgrade ssd that plugs in the back is based on same type of flash nand that used with digital camera's which is supposed to have a good wear limit but again take all that with a pinch of salt because I don't know for sure it's correct, just things I have read in past.