The bug:

Since 1.19.4 Pre-release 2, certain mobs with passenger(s) riding them are no longer able to attack/target players or other mobs.

List of affected mobs:

• Bee (When hostile)
• Blaze
• Cave Spider
• Creeper
• Drowned
• Elder Guardian (Still gives players mining fatigue, thorns still damages players)
• Ender Dragon
• Enderman
• Endermite
• Guardian (Thorns still damages players)
• Husk
• Illusioner (Only does duplication spell)
• Iron Golem (When hostile)
• Llama (When hostile, doesn't spit)
• Magma Cube (Touching them will still harm players)
• Phantom
• Pillager
• Polar Bear (When hostile)
• Ravager
• Shulker
• Silverfish
• Skeleton
• Slime (Touching them will still harm players)
• Spider (Note: MC-236303)
• Stray
• Vex
• Vindicator
• Witch
• Wither Skeleton
• Wolf (When hostile)
• Zombie
• Zombie Villager
• Zombified Piglin

List of unaffected mobs:

• Evoker (Still does magic attacks)
• Ghast (Still shoots fireballs at players)
• Piglin (Will even fire a Crossbow at players)
• Piglin Brute
• Hoglin
• Wither
• Zoglin

Expected Behavior:

Previous to this update, these mobs with passenger(s) riding them were still able to attack/target players or other mobs.

How to reproduce:

1. Launch a world in Minecraft 1.19.4.
2. Run (if summoning mobs that burn in daylight):

   /time set night

3. Run:

   /summon <any mob from list> ~ ~ ~ {Passengers:[{id:"minecraft:zombie",Attributes:[{Base:0.0d,Name:"minecraft:generic.attack_damage"}]}]}

4. Go into survival or adventure mode.
   →  The mob doesn't attack you.