@futurebird generally it's streamers or youtubers who instead of presenting themselves on screen using a webcam will use an animated character and sometimes altered voice to present their on screen persona. Typically the animated character will move in ways synchronised with that of the user via motion tracking, for greater verisimilitude.
I follow very few of them but found the trend curious enough to look into when they first started popping up.
It's a neat way of being able to have a consistent screen presence without having to expose your actual physical form. It also makes it easier to produce videos in a familiar and consistent format without needing physical space, green screen, makeup, etc.