Earlier today Apple released watchOS 6 beta 2, iOS 13 beta 2, macOS Catalina Beta 2 and tvOS 13 beta2 for registered developers.
Apple does add a warning in this beta
Your Secure Token might be lost if FileVault is enabled on a non-APFS formatted volume while upgrading to macOS 10.15. You might be able to work around this by disabling FileVault before upgrading to macOS 10.15, then reenabling FileVault once the upgrade has completed. (51091312)
MacOS Catalina 10.15 Beta 2… by on Scribd