Are they trying to make people quit playing terraria because that’s what it seems like to me
Nope.
When wearing a familiar shirt it will cause the Arkhalis and yoyos to be invisible.
This is known and has been reported. It seems to just be the Familiar Clothes.
Just confirming TK's statement here. Its known and been reported (iirc a user here had a video/gif of it a week or so ago when this first surfaced, using the Arkhalis).