At June, 19th the update "Fear the Rampager" was being published on all platforms except GOG. The last update published on GOG was "Rise of the Giant" from March, 28th. On GOG all updates ever since are missing, i.e. Update 13 Alpha (May, 7th), Update 13 Final (May, 23rd), Update 13.5 (June, 14th) and now even the major DLC "Fear the Rampager".

Wtf is going on with GOG?

Today, June 24th, the "Fear the Rampager" update is finally alive on GOG. That's five days after the release and it's the first published update on GOG since the end of March 2019.

Are we second class customers? Is our money not good enough?

It seems so. Mods are also "Steam-only". I'll definitely gonna think twice about buying from GOG instead of Steam in the future.