PaterAlf: I really wonder how it works. Some of the avatars are visible now, (like moonshineshadow oder Habenerose) some of the others that were apparently changed before can still not be seen (e.g. mateusbond, Fantasysci5).
The account database is large enough that iterating through it won't be instantaneous. There's also the order in which GOG applies it (account database ID, alphabetical, ???). Account IDs would all have been changed with the migration to Galaxy accounts. Additionally there is the front-end caching to deal with. I'm not surprised they weren't all changed at the exact same time.
Yesterdays changes all appear updated now for me. Of course I don't actually know what GOG's doing. For all I know they have
Judas randomly run the script, A-N then M-Z hours later, during his workday.