Trident, when thrown, seems to affect how nearby entities look in the same light level. The effect can disappear when player's camera is placed in a different angle, or when player is close to the trident. Similar thing happens even with enchanted trident.
Steps to reproduce:
1. Throw the trident on the ground or directly on the mob (the effect is similar in mid-air, but it lasts much shorter)
2. If necessary, adjust the player's position to see the effect
The glitch is best visible on the screenshot titled "5"