The Bug

If the player rings a bell and any raid-participating mob is nearby, it will get illuminated by the Glowing effect.

The most common occurrence would probably be witches, since witches can spawn as a 'common' hostile mob in dark areas such as caves and at nighttime. Vindicators/evokers can spawn in woodland mansions, allowing them to also get the Glowing effect, but this is much less likely.

It would be expected that only mobs who actively participate in raids are given the Glowing effect, and others would be ignored.

How to Reproduce

1. Place down a bell, and summon a mob that spawns in raids (such as a witch) near the bell (within 32 blocks of it).
2. Ring the bell while the mob is near it.
3. Note how the mob gets the Glowing effect even though it did not spawn as part of a raid.