If you count the amount of pixels from top to bottom of the potted cactus, they total to 17, even though blocks should only be 16 pixels tall.
A fix for this can be found attached to MC-194192
Linked issues
relates to 8
MC-120417
Incorrect dragon egg block model
Resolved
MC-194192
The bottom face of potted cactus is different from the bottom of regular flower pots
Open
MC-100929
Armor shoulders and boots are slightly squished
Open
MC-122701
Sunflowers are stretched
Open
MC-111506
Elytra has stretched texture on sides
Resolved
3 more links
In 20w29a