Unlike other 2-ID plants like kelp, twisting vines and weeping vines, cave vines use the same display name "Cave Vines" for both IDs.
The display names should be "Cave Vines" for the head, and "Cave Vines Plant" for the body, to be consistent with the other plants.
Steps to reproduce:
/give @s stick{CanPlaceOn:["cave_vines_body","cave_vines_head"]}
Look at the display names in the item lore.
Note:
Unlike wall banners (MC-124142) the cave vines do have separate translation keys.
Does MC-213911 describe this issue?