Blue dot in top right corner of screen changes size too

I fail to find the origin of a blue dot appearing in the top right corner of the screen. Is this a bug or a feature? edit: add screenshot if said dot https://preview.redd.it/guo3eu7l3hce1.jpg?width=58&format=pjpg&auto=webp&s=eda614d55778b1d93fabe5a52d0af099ff5977fc