Paper: Rideable entities are able to desync

[Paralusion]

What behaviour is expected:

___What you expected to see___
As soon as you dismount the entity (client-sidely), you'd get kicked for inappropriate behaviour.

What behaviour is observed:

___What you actually saw___
You can client-sidely dismount the entity and therefor desync it from the server, meaning you can do a lot of stuff with it, such as bypassing anti-cheats.

Steps/models to reproduce:

Client-sidely dismount the entity
___This may include a build schematic, a video, or detailed instructions to help reconstruct the issue___

Plugin list:

Does not matter
___A list of your plugins___

Paper build number:

Does not matter
___This can be found by running /version on your server. latest is not a proper version number; we require the output of /version so we can properly track down the issue.___

Anything else:

___Anything else you think may help us resolve the problem___

[zachbr]

Try again, fill out the template completely. We decide what does and doesn't matter, not you.

[VADemon]

https://bugs.mojang.com/browse/MC-101247 ?

[Paralusion]

Plugin list: None
Paper build number: 1681

[zachbr]

That's just exceedingly unfortunate timing on your part. Support for MC 1.12.2 was dropped this morning.