Found this on Reddit, but haven't tried it yet:
Note this is only for if you just want to play, you wont have access to your saves. Including the next time you start the game and it wants to sync again. Hopefully a hotfix comes soon.
- Start / menu button on Terraria -> manage game and add-ons
- Go down to save data, delete all save data.
- When the game starts it will try to sync your save data from the cloud. CANCEL the sync. It will ask if you are sure you need to QUICKLY move to the right and say yes cancel, or it will sync anyways.
- Play game.