Signal is my only instant messenger and I can happily report no issues these days with notifications, that said, I never really noticed them previously and have been using for >3 years.

Occasionally we’ll use Signal whilst on a live call, someone will tell us they messaged on Signal and I’ll get the notification immediately - i.e. I knew when it was sent and received.

This is working smoothly on my grapheneos phone and the desktop client across Linux and Windows.

You’ve opened a rabbit hole I know I’m just going to fall down… thanks netizen!