GOGMixes had been broken since August, with at least two people reporting that they got replies from support that they were abandoned, and now it's official that they were removed from game pages and are no longer considered a site feature (though if you have the links they're still there for now, but can no longer be updated since August). There was a blue post indicating that there may be something done about it eventually, but I took it as a way for people to make "curated collections", which at the moment just seem to redirect to a bunch of games in the catalog listing, no comments, ratings and sorting by the creator.
