PaperMC/paper-server/nms-patches/net/minecraft/world/entity/monster/EntityWitch.patch

--- a/net/minecraft/world/entity/monster/EntityWitch.java
+++ b/net/minecraft/world/entity/monster/EntityWitch.java
@@ -124,7 +124,7 @@
                     PotionContents potioncontents = (PotionContents) itemstack.get(DataComponents.POTION_CONTENTS);
 
                     if (itemstack.is(Items.POTION) && potioncontents != null) {
-                        potioncontents.forEachEffect(this::addEffect);
+                        potioncontents.forEachEffect((effect) -> this.addEffect(effect, org.bukkit.event.entity.EntityPotionEffectEvent.Cause.ATTACK)); // CraftBukkit
                     }
 
                     this.gameEvent(GameEvent.DRINK);