You can see for yourself here -- its last update here was 16 month ago. I don't know what the most recently released version is overall, though, nor when the Steam version last got a major update.

I do not know how exactly I find 2 those pages (https://www.gogdb.org/product/1960384075/build/55928971851445126 ; https://steamdb.info/app/252610/patchnotes/) but I think I found the core of truth. So I researched that the situation with both updates is the same with both GOG and Steam versions. Both versions have the same major update - NERVE Update, both versions were updated around the same time - 2022-10. In fact, Steam users can activate the Beta branch for the game, and as I understand GOG users do not have such an option. So both versions are pretty the same in terms of content (of course if we forget about the Beta branch in the Steam version of the game).
That was not too easy to find out, but at the same time, I cannot say that it was an impossible task.

The latest version is called Omentum (probably because O was next). Let's see if it turns up here.