Even if you're not raiding, when a witch attacks a ravager or witch, it attacks them with a healing potion or a regeneration potion

Very simple steps to reproduce:

1. Summon a vindicator as having this NBT. /summon vindicator ~ ~ ~ {PersistenceRequired:1b,Johnny:1b,PatrolLeader:1b,Patrolling:1b,CanJoinRaid:1b}
2. Reproduce as shown in the screenshot