It looks like the reason is in the latest firmware 2101.2.
I found a pattern that U-series TVs of different models were no longer available for control in SmartThings, and when trying to initially set up the TV through SmartThings after a reset, the user receives an error 07-005 or 07-007 and the TV can only be configured from the remote control. All these TVs have one thing in common: they have the same firmware version 2101.2.
The release time of the firmware just coincides with the beginning of problems in the form of the inability to control TV through SmartThings.
Samsung needs to release a patched version of the firmware.