WinterSnowfall: Huh... my library count has also dropped by 3 :|. But it's none of the titles that are mentioned in the above linked thread. Guess someone will figure out what's missing soon enough.
P.S.: Seven: Enhanced Edition has resurfaced at the top of my list, as is usually the case when GOG refreshes accounts on its own, so hmmmm indeed.
The number of games in my account is as it should be, the games mentioned as missing from accounts in this comment
https://www.gog.com/forum/general/gog_if_you_want_to_attract_new_customers/post154 are all still here
(as far as I own them), and "Seven: Enhanced Edition" is not at the first position on my shelf - yet.
But from experience I know that that can take a while to affect all owners
(and it's really no biggie, since at some point, it returns back to its rightful place).