It's normal, the item placed on an item frame or in the creative menu, will look different compared to the block placed because it is a representation, it dosen't need to be exactly equal.
Mending Enchanted Book has the same problem
I have tested it on a 1.14.4 world, and it still having 19x19 entity processing chunks.
user-7c910
It's normal, the item placed on an item frame or in the creative menu, will look different compared to the block placed because it is a representation, it dosen't need to be exactly equal.