Don't Install iPadOS 13 Beta If You Jailbreak
If your iPad is jailbroken or you want to jailbreak your device, avoid the beta for now.
Jailbreak developers have released iOS 12 jailbreak tools for older versions of iOS 12, but we haven't seen anything for the iOS 12.4, iOS 12.3.1, iOS 12.3, iOS 12.2, iOS 12.1.4, or iOS 12.1.3.
We've seen an iOS 13 beta jailbreak emerge, but we'd be surprised if developers burned their exploits on a beta. We probably won't see a public release ahead of the official iPadOS 13 release this fall.
If you want to jailbreak your tablet it needs to be on an old version of iOS 12, iOS 11, or iOS 10. Unfortunately, there's no way to downgrade to any of those updates.