Teleporting a player at the right moment can mess upp vanilla teleportation

[Thorinwasher]

Expected behavior

The vanilla teleportation behavior should either:

1. Send the player to a different dimension, and to the right location, as if the player teleported from the location that triggered this event.
2. Not trigger at all, as the player nolonger is at the original location

Observed/Actual behavior

In some cases the player teleports monodimensionally (Race condition?), also generating a destination portal, if necessary.

Steps/models to reproduce

Monodimensionall travel can be reproduced with this minimal(ish) reproducible script:

@EventHandler
    void onPlayerMove(PlayerMoveEvent event) {
        Location to = event.getTo();
        Location from = event.getFrom();
        if (from.getBlockX() == to.getBlockX() &&
                from.getBlockY() == to.getBlockY() &&
                from.getBlockZ() == to.getBlockZ()) {
            return;
        }
        Material toType = to.getBlock().getType();
        if (!Tag.PORTALS.isTagged(toType) || toType == Material.END_GATEWAY) {
            return;
        }
        World originWorld = to.getWorld();
        World targetWorld = switch (originWorld.getName()) {
            case "world" -> {
                if (toType == Material.END_PORTAL) {
                    yield Bukkit.getWorld("world_the_end");
                }
                yield Bukkit.getWorld("world_nether");
            }
            default -> Bukkit.getWorld("world");
        };
        Bukkit.getScheduler().runTask(this, () -> {
            event.getPlayer().teleport(new Location(targetWorld, to.getBlockX(), to.getBlockX(), to.getBlockZ()));
        });
    }

To reproduce

1. Start a new server with default world names with a plugin that contains the given script
2. Make a nether portal
3. Go through the nether portal in creative mode (not flying)

Plugin and Datapack List

Only testplugin

Paper version

This server is running Paper version 1.21-9-master@4ea696f (2024-06-19T04:26:57Z) (Implementing API version 1.21-R0.1-SNAPSHOT) You are running the latest version Previous version: 1.21-DEV-c1aefee (MC: 1.21)

Other

Probably reproducible for entities as well. Can probably also be reproducible with end portals