Too many pictures to report. People have found a way to replace or even add other items / blocks to the one item frame. Such as the grass block being replaced, all dyes replaced with other items, sword + slime ball in one frame. I don't even know my way around the shop now!
Sorry, but no. I haven't seen other people do this, but I do find this a nuisance, as it would mislead people. Like the time I was trying to find the section where to sell grass blocks.
Hmmm, I got a poopy solution lol, maybe put something invisible in front of the item frames so people can't hit it?
Could've been something with throwing projectiles at the item frames, as there was a bug with that yesterday. However, that bug is now fixed so let's see if people are still able to put items in the item frames. (I've left them empty until I'm sure the problem is fixed).