Fedi pls help

How is this Android UI component called? I need API documentation on it, but I can't remember its name. It doesn't seem to be an "alert". It shows on top of everything even if you exit the app. Sometimes it may show the caller's app icon.

https://cdn.pony.social/media_attachments/files/111/023/526/369/196/985/original/d557fe90e88de990.png