PaperMC/paper-server/nms-patches/ItemPotion.patch

--- a/net/minecraft/server/ItemPotion.java
+++ b/net/minecraft/server/ItemPotion.java
@@ -30,7 +30,7 @@
                 if (mobeffect.getMobEffect().isInstant()) {
                     mobeffect.getMobEffect().applyInstantEffect(entityhuman, entityhuman, entityliving, mobeffect.getAmplifier(), 1.0D);
                 } else {
-                    entityliving.addEffect(new MobEffect(mobeffect));
+                    entityliving.addEffect(new MobEffect(mobeffect), org.bukkit.event.entity.EntityPotionEffectEvent.Cause.POTION_DRINK); // CraftBukkit
                 }
             }
         }