The bug

You cannot place item frames and glow item frames at the build height limit even though they are entities and boats and armor stands can be placed on top. It also doesn’t give any error message when trying to place them. You can however get them there using commands.

How to reproduce:

1. If you are in the overworld:

   /setblock ~ 319 ~ minecraft:netherite_block

   and in the nether or the end

   /setblock ~ 255 ~ minecraft:netherite_block

2. Go on top of the netherite block
3. Try to place an item frame or a glow item frame
   Nothing happens, no error message and nothing was placed, if try to do it with a boat or an armor stand, it will work.