Paper/patches/server/0789-Ensure-entity-passenger-world-matches-ridden-entity.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Thu, 31 Mar 2022 05:11:37 -0700
Subject: [PATCH] Ensure entity passenger world matches ridden entity

Bad plugins doing this would cause some obvious problems...

diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index 70b69359002b283645ead0af0e1b1a7a9fb9a60c..7c6f9abfbe3528705766b94879a20b001f3a04ad 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -2841,7 +2841,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource {
     }
 
     public boolean startRiding(Entity entity, boolean force) {
-        if (entity == this.vehicle) {
+        if (entity == this.vehicle || entity.level != this.level) { // Paper - check level
             return false;
         } else if (!entity.couldAcceptPassenger()) {
             return false;