The Bug:
When any type of boat or raft is near a painting or item frame, it will break it off; even invulnerable paintings are affected by this, but not fixed ones.
Minecarts, horses and armour stands don't break off paintings or item frames so this is likely unintended behaviour.
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How to Reproduce:
1. Get an item frame or a painting, and then place that painting/item frame down somewhere.
2. Equip any type of boat or raft, place it down, and get in the boat that you just placed down.
3. Touch/be near the item frame/painting with the boat or raft.
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Confirmed in 1.16.1 and 20w29a. Affects even invulnerable paintings and item frames, though not fixed item frames.