Potion effects don't affect player FOVs when the player is spectating an entity

The Bug

While a player is spectating another entity, such as another player, the spectator's FOV will not be affected by either the spectator itself or the spectated mob's speed/slowness effects.

To Reproduce

1. Summon a zombie and splash it with a potion of slowness.

2. Give yourself the slowness effect by using the command provided below.

   /effect give @s minecraft:slowness infinite 10 true

3. Switch to spectator, spectate the zombie, and observe your FOV.