Version: extraboats-1.16.5-2.1.0.jar

Steps to reproduce:
Make a chest boat, shift+right click to open the chest.
Insert an item (like an Oak sapling).
Pick up the boat by shift+right clicking the front of the boat with empty hands (no primary or off-hand item).
Place the boat back down, put something in your hands and shift-right click the chest again.
Items will be lost.

Secondary bug:
Reproduce the steps above, but with a boat of a different wood type (like Spruce for example).
After picking up the boat, it changes to an Oak type, rather than the one it was initially made out of.

...? What are you using to pick-up the boats?

NM, Figured out what was causing it. The CarryOn mod (blacklisted these boat so it's a non-issue now).