No idea, I just know that I created a wishlist about it years ago.
The clause is good IMO, but then it should have N warnings until a penalty (e.g: higher store %) or a final removal.
Basically it should only affect the worst devs, not a small indie company late by 3 days a few times.

Not sure where you'd put this, but, as I mentioned in an earlier post, Battle Chasers: Nightwars promised a Linux version (Oct. 2017) and only delivered on Steam (May 2018). I was reminded of this again because they released a minor patch to the Windows version just today.

A couple I've seen reported around the forums here recently, but cannot confirm myself:

The Book of Unwritten Tales 2 and The Raven Remastered (SOURCE) Caves of Qud (SOURCE) Normally I wouldn't have jumped the gun on the Caves of Qud one since it's only been a few days, but the poster says that the Linux version is even further out-of-date.

1) Tested BOUT 2 and unfortunately it really is outdated.
https://store.steampowered.com/news/?appids=279940
French, Italian and Spanish subs are missing and the game also did not receive the patch from 03/16/2015 (no changelog). Version is 1.0.1.3.1. However same version on Galaxy exclusive update possible as well. This game is outdated and we should tell THQ Nordic asap.

2) The Raven Remastered is also outdated. It has never been updated on GOG since its release which was on 03/12/2018. The only patch (at least for Windows which should fix a resolution error on launch) has been released on Steam on 04/04 see here. GOGs version is 1.1.0.654 and again, Galaxy version is the same.

Enclave (one of my all time favs from the Xbox days) is lacking on GOG... Steam got a Digital Deluxe Edition while GOG just has the game itself

https://store.steampowered.com/bundle/9357/Enclave__Digital_Deluxe_Version/

Add Q.U.B.E. 2 to the list... last developer update was 1.5 (the 1.6 that GOG shows was just GOG adding Overlay support) and Steam has a 1.7 update that was released back in September

https://steamcommunity.com/games/359100/announcements/detail/1692681328289977638

Planning to update this week, family stuff been going on. Sorry about it taking a while.

Hand of Fate 1 finally got updated to the latest 1.3.20 version, now matching the Steam version number. I asked Judas about it a bit ago and it got updated a bit after that so i'm not sure if that's why it finally got the latest patch. It does seem to be missing some sort of leaderboard system that exists in the Steam version, but i'm not sure if that qualifies it to wind up on this list. The store page on Steam says "Steam Leaderboards" so i'm guessing it's a functionality tied to Steam and the devs don't have a leaderboard system in place independent of Steam.

A couple of suggestions for removal from the list:

Botanicula DLC
"The Humble-exclusive bonus content showed up 5 years later without a free upgrade for GOG users."

This was never free DLC on any store. It's part of a higher-priced edition on Humble, and separate paid DLC elsewhere.

It *was* part of the launch day Humble Bundle, but that fiasco only affected people who'd pre-ordered Botanicula, and they received the bonus content (along with Machinarium and The Witcher) at the time to make up for it. Adding this DLC to GOG redressed the issue of it being unavailable here - it seems wrong to criticize Amanita for not making it free just because it was available cheaply in a Humble Bundle 6 years ago.

The Final Station
"Missing Collector's Edition"

We have this. As the Steam page shows, the Collector's Edition is just a bundle of the base game and its two DLCs ("Art Book & Soundtrack", "The Only Traitor") with a 10% discount. GOG has exactly the same offer. It was advertised in the news release for The Only Traitor. It's also shown on The Final Station's game page, but good luck finding it. GOG's new layout makes bundle deals like this practically invisible by calculating the discounted price and putting it in a greyed-out font under the "Why buy on GOG.com" section. Sigh.

Surprising but also rather pleasing :D

Great news! I wish they'd perform the same magic on Hybrid Wars, which also has free single-player content (a new character, Ivan) locked behind connecting up with the wargaming.net servers. This sort of thing sits poorly with the GOG DRM-free mentality, since the free extras are lost forever when linkups with 3rd parties become unavailable.

Yes, I know. I already tried to find a way to get this unlocked but since the devs see this character as a reward for accessing MP (including signing up to a third party account) I doubt they will change this. I am glad however that GOG meanwhile changed the gamecard to reflect this necessity for people that have not bought the game yet. It's not good but it's better.

Hybrid Wars, Battletech and X4: Foundations are the games of my knowledge that have the same problem as DLC blocked upon registration to a third party account and one-time/constant online connection for access them.

Now, if only finkleroy wanted to buy them and then threaten GOG's support to want a refund, maybe we could solve the problem...

So far we f finkleroys threat has been the reason GOG fixed Daylight and tbh I would really be interested to hear GOGs reason and if THEY fixed it or Techland or if they pushed Techland a bit to fix it ... really curious here but I doubt I will get an answer.

But I did not know that even more games here on GOG - the DRM-free(!) store - are affected. Does GOG know?