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

--- a/net/minecraft/server/EntityWitch.java
+++ b/net/minecraft/server/EntityWitch.java
@@ -93,7 +93,7 @@
                             while (iterator.hasNext()) {
                                 MobEffect mobeffect = (MobEffect) iterator.next();
 
-                                this.addEffect(new MobEffect(mobeffect));
+                                this.addEffect(new MobEffect(mobeffect), org.bukkit.event.entity.EntityPotionEffectEvent.Cause.ATTACK); // CraftBukkit
                             }
                         }
                     }