PaperMC/paper-server/patches/sources/net/minecraft/world/item/SplashPotionItem.java.patch

--- a/net/minecraft/world/item/SplashPotionItem.java
+++ b/net/minecraft/world/item/SplashPotionItem.java
@@ -14,6 +_,10 @@
 
     @Override
     public InteractionResult use(Level level, Player player, InteractionHand hand) {
+        // Paper start - PlayerLaunchProjectileEvent
+        final InteractionResult wrapper = super.use(level, player, hand);
+        if (wrapper instanceof InteractionResult.Fail) return wrapper;
+        // Paper end - PlayerLaunchProjectileEvent
         level.playSound(
             null,
             player.getX(),
@@ -24,6 +_,6 @@
             0.5F,
             0.4F / (level.getRandom().nextFloat() * 0.4F + 0.8F)
         );
-        return super.use(level, player, hand);
+        return wrapper; // Paper - PlayerLaunchProjectileEvent
     }
 }