The OneUI 3.0 Beta 4 update comes with build version ZTLL. The update is currently being rolled out in Korea via an OTA (Over-the-air) update.

Changelog of Beta 4 One UI 3.0

-Quick panel cannot be touched when Close> Open-When switching to window mode, it moves to the bottom of the screen and does not move -Security folder backup is not possible after FOTA-After running the camera in the unfolding state> Lightly folding> FC -Settings> All Selecting an app from the app to use as the aspect ratio does not apply. -Multi Window operation error -Quick panel> Music control bar cut off -When calling apps> Blur may not be applied The update is rolling out to those users who have joined the OneUI beta program. To join the beta program, head to Samsung Member app and join the beta program. Non-beta users will have a wait for some time to get a stable update.
Source

 Beta 4  OneUI 3 0 ZTLL update for Galaxy Z Fold 2 - 63