The Bug:

Bad omen is not granted when pillager captains are killed by trusted foxes.

The player receives the bad omen effect when their tamed wolves kill pillager captains, therefore one would expect the same thing to occur when trusted foxes kill pillager captains.

Steps to Reproduce:

1. Summon two foxes and breed them using sweet berries.
2. Place down a command block and input the command provided below into it.

   /summon minecraft:pillager ~ ~1 ~ {Health:3f,PatrolLeader:1b,HandItems:[{id:"minecraft:crossbow",Count:1b},{}],ArmorItems:[{},{},{},{id:"minecraft:white_banner",Count:1b,tag:{HideFlags:32,BlockEntityTag:{Patterns:[{Pattern:"mr",Color:9},{Pattern:"bs",Color:8},{Pattern:"cs",Color:7},{Pattern:"bo",Color:8},{Pattern:"ms",Color:15},{Pattern:"hh",Color:8},{Pattern:"mc",Color:8},{Pattern:"bo",Color:15}],id:"minecraft:banner"},display:{Name:'{"color":"gold","translate":"block.minecraft.ominous_banner"}'}}}]}

3. Power the command block in order to summon a pillager captain.
4. Switch to survival mode, punch the pillager captain, and allow it to attack you.
5. Wait for the trusted fox to kill the pillager captain.
6. Take note as to whether or not bad omen is not granted when pillager captains are killed by trusted foxes.

Observed Behavior:

The player is not granted the bad omen effect.

Expected Behavior:

The player would be granted the bad omen effect.