Okay, what does the little "spark" indicate? When I press/hold on the icon, nothing special pops up and it does not clear the spark/dot. And sometimes I find nothing special in Notifications either.
That's the notification dot in the stock launcher (possibly others as well). Just deselect it in Settings > Apps if you don't want it. View attachment 359422
It should indicate a notification for that app. The next time you see a notification dot but no associated notification in the swipedown panel, take some more screenshots and show us.