Since it's missing from the OP, here's the thread on GOG's own forum where people report those issues, and with the Google doc attached to the opening post:

https://www.gog.com/forum/general/games_that_treat_gog_customers_as_second_class_citizens_v2/post1

I guess games being older versions than on Steam? And maybe unavailable features and content?

It's a spreadsheet of games along with omissions and missing features that are only missing on GOG.

I remember a developer complaining that getting updates approved in GOG takes significantly more time than on Steam, so GOG is partially at fault, too. Wish I could find the source on that

100% all of it.

Lemmings don't understand nuance, they just know they're supposed to glaze GoG because "Steam bad" and "Steam unc"

One game that I want to buy on gog but have paused on is Wreckreation (Dangerous Driving 2 aka 'Burnout reborn'), as the gog version doesn't have any multiplayer, while the steam version does. This is a big deal since the entire 'spin' in this follow-up is 'make tracks, jumps, stunts, and havoc with your friends in real-time, involving the game world at ground level or the open space sky-high'. Up until recently the gog page listed multiplayer as a feature, even though reviews and forum posts say that is not true.

Though Dangerous Driving 1 promised to release on Steam (promotional materials, videos, website...), then bent over and took a cash enema from Daddy Epic, and never released on steam at all. So I might just pirate Wreckreation too, because they clearly want profits over what their users want (honesty, choice, transparency, and equal treatment).

It's not rare for games on gog to be abandoned but maintained on steam, was hit often enough myself.

And while it makes business sense, it is a bad thing. It should not be released there if, yes, you're being treated second class.

Aside from missing content or features one of the most common issues would be for multi-player not being included, working or incompatible. Sometimes without being transparent about it.

How is that not second class?

Edit:

I feel some are missing the context here. The title is that games are treating gog customers second class.

It's not about gog themselves being bad, I am actually a major proponent of gog and they're my first choice. The situation is regrettable and the source of the issue is often or mostly the developer of a game that chooses to release on gog but doesn't go as far as to maintain the release.

It's Lemmy. We're supposed to have a hate-boner for Valve and Steam here, so any reason to put GoG on a pedestal or pretend Steam is "literally EA" gets upvoted and circle jerked