In the update log (https://www.minecraft.net/en-us/article/minecraft-snapshot-23w06a), it said item_display defaults to "none". However, In the game, its default value is "fixed" instead of none. Not sure if this is intended.
How to reproduce:
summon an Item Display: /summon item_display
view its data: /data get entity @e[limit=1,type=item_display] item_display
Note:The transformations of "fixed" and "none" seem reversed, as described in MC-260175. But I can't reproduce it.
Although MC-260175 mentions that the two transformations are reversed, I failed to reproduce it