When a shulker/boat is on a block, and you have auto-jump activated, you will jump (but fail) on the block.
Linked issues
relates to 2
Attachments
Comments 6
Confirmed for 1.13.1.
Thank you for pointing this out, Tan Chin. I see why this happens, it is because autojump does not take entities into account. If it did this, than auto jump might be more laggy.

Confirmed in 1.16.1 and 20w28a.
Confirmed for 21w07a
Can confirm in 1.19.4-rc2.
This issue relates to MC-103913 / MC-103236.