Samsung started Roll out the A UI 4.0 update to Galaxy Z Flip3 and Z-fold 3 Owned in South Korea a few days ago, but users report a variety of issues with the new version. It appears that Samsung has temporarily withdrawn the update while investigating the issues.
The mentioned issues range from the phone blocking or sending to recovery mode to reduced performance and screen flicker. Some users have also reported issues with the camera app and that the dual messenger feature is not working with some apps.
It is not clear when the update rollout will resume (or extend to other countries). Samsung employees are speaking to affected consumers to help resolve the issues.