Virtually no mod support, despite it being a proclaimed feature. There are countless mods available on the Steam workshop, including several that featured when the dev announced mod support, but they aren't available anywhere else. Dev locked away public access to the Steam workshop too, so GoG users can't simply download them. If you're considering this game, get it on Steam or not at all.
I'm probably one of the few who isn't impressed by the ReSubmerged update. Yes, it's made the game a lot prettier, but it's introduced 36 officially recognised MAJOR bugs (some of them gamebreaking) and it removed the interesting Oxygen and Food mechanic. It's like that meme, "Upgrade, upgrade, GO BACK!!!" But we can't go back... :(