To reproduce this, you need to use 2 players, 1 to continue the chunk loading and the other to reproduce it

1. Apply invisibility effect:

   /effect give @p minecraft:invisibility infinite 255 true
   

1. Summon 10 or more of the affected mobs
2. Attack one of the affected mobs
3. Dies

As you can see, even if a player dies, as long as they don't leave the server, the mob will have permanent infinite detection range and impaired attack behavior

Thus, mobs can respawn kills players

The following mobs are known to be affected:

• 'Illager' mobs (evokers, pillagers, vindicators, and illusioners)
• Ravagers
• Wolves
• Zombie mobs (zombies, drowned, husks, zombie Villagers