The mod UI Tweaks has been recently updated in the Steam Workshop, but hasn’t been resanctioned.
I ran the game after the mod has been updated and got “Server Error - Backend rejected the challenge response”, and “State: Untrusted - Unknown file version […]” error messages suggesting that this is because the unsanctioned UI Tweaks mod has been enabled. Screenshot:
I have checked “Auto-disable Unsanctioned Mods in Official Realm” in the game launcher so UI Tweaks should have been automatically disabled as an unsanctioned mod, but the setting didn’t work. I had to manually disable the mod to play the game in the official realm.