This does not happen when I join a world in 1.16.1, and seems that it is not a bug in Minecraft, rather a problem with your computer! This makes the current issue invalid.
Hi there! Don't quote me, but I assume this is working as intended as armor stands with "Invisible" set to 1b don't show their hitboxes either.
My mistake =) thought unreleased versions meant snapshots.
TheoSauce
This does not happen when I join a world in 1.16.1, and seems that it is not a bug in Minecraft, rather a problem with your computer! This makes the current issue invalid.