This relates to MC-250216, MC-250207, MC-250183, and MC-250198.

The bug:
If the warden is angered by a target and that mob despawns, the warden will continue to roar at the target until the anger value towards the target goes below 80.

Steps to reproduce: (You don't need to create a scoreboard to see the anger value, but it can be useful visually seeing it)

• Create a scoreboard with the commands below

  /scoreboard objectives add WardenAnger dummy
  /scoreboard objectives setdisplay sidebar WardenAnger
  

• Inside of a repeating command block that is always active, enter this command.

  execute as @e[type=minecraft:warden,limit=1] at @s store result score AngerLevel WardenAnger run data get entity @s anger.suspects[0].anger
  

• Fly high enough to where two 1 block platforms, one with a warden and one with a creeper can be placed without obstruction using the commands below.

  /fill ~ ~-4 ~ ~ ~-4 ~ stone
  /fill ~10 ~-4 ~ ~10 ~-4 ~ stone
  /summon minecraft:warden ~ ~-3 ~ {anger:{suspects:[{uuid:[1,1,1,1],anger:150}]},PersistenceRequired:1b,Brain:{memories:{"minecraft:dig_cooldown":{value: {}, ttl: 1200L}}}}
  /summon creeper ~10 ~4 ~ {UUID:[I;1,1,1,1]}
  

• Once the warden's roars use the commands below
  /tp @s ~-128 ~ ~ -90 20
  /tp @s ~120 ~ ~5 -110 20
  The creeper should have despawned.

Observed result:
The warden will roar continuously until the wardens anger value towards the despawned creeper goes below 80

Expected result:
The creeper no longer exists. The warden shouldn't try to kill something that doesn't exist.