Once I saw that all of my extensions were crashing and I was notified about that by notifications from Edge but the difference I spotted is that they were Edge designed notifications rather than the default Windows 10 one as shown in the screenshot. They had a very nice animation that they would slide from the right and then and it would go by shrinking itself into a point just like a pinch rather than the slightly broken animation that the default Windows 10 one has and also they can stay on top of each other which the Windows 10 one cannot. So, I am suggesting that all notifications should be the Edge designed ones because they look better and work very properly than the default Windows 10 one.
The extension has crashed notification which has its own Edge notifications UI
If you like this suggestion, then please send feedback about it through the in-app feedback tool (Alt+Shift+I) in Microsoft Edge to give it a +1 to make it a part of Microsoft Edge in the future.