Chrome Version: 70.0.3532.8
OS: ChromeOS

What steps will reproduce the problem?
(1) Sign-in to chat.google.com and enable notifications, or Hangouts extension.
(2) Allow the site/extension to show notifications.
(3) Leave the device idle, while people message you.

What is the expected result?

Come back to some small number of notifications, for recent messages.

What happens instead?

On resume, each and every message sent in the meantime has its own notification, so you're stuck with ~1/2 of one edge of the screen consumed by notifications. Closing one of them just makes space for another one that hasn't yet been shown.

Not sure if this regressed in M69 or in M70, but it has been broken for at least ~weeks.