PaperMC/paper-server/nms-patches/net/minecraft/world/effect/MobEffectUtil.patch

--- a/net/minecraft/world/effect/MobEffectUtil.java
+++ b/net/minecraft/world/effect/MobEffectUtil.java
@@ -50,13 +50,19 @@
     }
 
     public static List<EntityPlayer> addEffectToPlayersAround(WorldServer worldserver, @Nullable Entity entity, Vec3D vec3d, double d0, MobEffect mobeffect, int i) {
+        // CraftBukkit start
+        return addEffectToPlayersAround(worldserver, entity, vec3d, d0, mobeffect, i, org.bukkit.event.entity.EntityPotionEffectEvent.Cause.UNKNOWN);
+    }
+
+    public static List<EntityPlayer> addEffectToPlayersAround(WorldServer worldserver, @Nullable Entity entity, Vec3D vec3d, double d0, MobEffect mobeffect, int i, org.bukkit.event.entity.EntityPotionEffectEvent.Cause cause) {
+        // CraftBukkit end
         Holder<MobEffectList> holder = mobeffect.getEffect();
         List<EntityPlayer> list = worldserver.getPlayers((entityplayer) -> {
             return entityplayer.gameMode.isSurvival() && (entity == null || !entity.isAlliedTo((Entity) entityplayer)) && vec3d.closerThan(entityplayer.position(), d0) && (!entityplayer.hasEffect(holder) || entityplayer.getEffect(holder).getAmplifier() < mobeffect.getAmplifier() || entityplayer.getEffect(holder).endsWithin(i - 1));
         });
 
         list.forEach((entityplayer) -> {
-            entityplayer.addEffect(new MobEffect(mobeffect), entity);
+            entityplayer.addEffect(new MobEffect(mobeffect), entity, cause); // CraftBukkit
         });
         return list;
     }