I'm not sure how many games this could be happening with, but for Enter the Gungeon I haven't been properly notified about any of the three most recent updates it has had. Is anyone else having this problem? Does GOG know about it?

Multiples: Gungeon, Crypt of the Necrodancer, Race the Sun, likely more.

I wish

Follow the thread instead:
https://www.gog.com/forum/general/the_what_did_just_update_thread

GOG's Update notification is BROKEN for quite a long time. :-/

Divine Dinity 2, Crypt of the Necrodancer: Amplified, Eador. Imperium, The Witcher 3, Project Zomboid...

Just to name a few.

I just run gogrepo.py update, and it will certainly notice if any games' installer/extras files have changed, no matter if there have been update notifications or not.

Another option would be to use Galaxy I guess, if you are so inclined.

I did get a notification for the latest Gungeon update, so that's good at least.

If only.. I have 130 useless notifications by now. :P
I basically ignore them and check the user-made update thread.