UI pattern to hint at important content outside of viewport

Does anyone know the name of the pattern where you add indicators that there is important content outside of the viewport?

I am trying to find some inspiration but for the love of God I can't find anything. The only example I can think of is Slack (see picture).

I need a solution that works both vertically and horizontally. The horizontal scroll is actually a carousel of columns that snap to a fixed position, it is not a continuous slide motion.

Any inspiration would help, it doesn't need to be a solution to my particular problem.