The bug

If you have semi-transparent entities inside a boat, for example if you are in a team and have the invisibility effect so that you see yourself transparently, you will not fully see yourself inside the boat when playing on fabulous. This does not happen on fast or fancy. Transparent dropped items have the exact same issue. Affected items are stained glass etc., but not regular glass.
Relates to MC-224703, MC-224242 and MC-183496.

How to reproduce

1. Dig a hole
2. Drop stained glass inside it
3. Place a boat
4. Play on fabulous
   →  You will not see the item while it is inside the boat