maximus87 I use google play services, and my notifications seem to be working fine. I don't have many apps allowed to send notifications except for Signal, the default GrapheneOS update notifications (of course), and a weather alert. Just a couple others, but those aren't daily and seem to be fine.
I've never received update notifications from either the Aurora store or Droid-ify, though. That's not new, and I can manually open those stores & check for apps needing updates, but have not received notifications about apps having updates, though. Not an issue for me, but figured its worth mentioning.