Steps to reproduce

1. Place a boat.
2. Spawn a pillager or skeleton so it gets stuck in the boat.
3. Spawn a parrot so it gets stuck in the boat.
4. Stand behind or to the side of the boat so that the pillager will try to shoot at you.
5. /gamemode s

Expected result

The pillager can shoot you over the parrot's head.

Actual result

The pillager's arrows get trapped in the air above the parrot and repeatedly make a sound like they are hitting something.

Included is a short demonstration video. When a Parrot and a Pillager enter a boat together, and the Pillager detects a player, it fires an arrow towards the player; depending on the trajectory of the shot, the arrow may get stuck in the top of the parrot's hitbox. The arrow continues to float there without despawning and the Pillager will continue to fire arrows as long as the player is in detection range. As each moving arrow is an entity, if enough arrows are left to accumulate it can cause massive lag, especially on a console world.

Edit: As the arrows are still "in motion" they are still active projectiles and will also cause damage to anything that bumps into them. Bug will also occur with Skeletons, as well as Pillagers, so if this gets marked as "works as intended" this floating arrow trick could potentially be exploited to design a nice music disc farm.