The bug
It is possible to place a pointed dripstone on top of another pointed dripstone with a player on the edge of the lower pointed dripstone, even though this changes the hitbox.
This is probably best to explain in video form: https://youtu.be/HUN5w-YniEY
At the end of the video, I attempt to sneak, but this is not possible when inside of another block, so nothing visibly changes.
How to reproduce
Place a pointed dripstone on the ground
Sneak and move to the side of the dripstone
Place another pointed dripstone above the bottom dripstone
Notice how the hitbox of the dripstone expands, and your hitbox is now inside of its hitbox
This has not been fixed, unfortunately.