The screen jitters when spectating players that are spectating other entities

The Bug:

When "Player A" spectates "Player B", if "Player B" was to spectate any other entity, "Player A"'s screen would jitter.

Steps to Reproduce:

1. Get two players and label them "Player A" and "Player B".

2. Get both players to switch into spectator mode.

3. Get "Player A" to spectate "Player B" using the "/spectate" command.

4. Get "Player B" to spectate any living entity.

5. Get "Player A" to watch their screen closely.

6. Take note as to whether or not the screen jitters when spectating players that are spectating other entities.

Observed Behavior:

The screen jitters.

Expected Behavior:

The screen would not jitter.