Our Engineering Team has implemented a fix, and we are monitoring the results. If you were logged out of your app, you can use the same device code to sign into the corresponding tablet or mobile device.
You can find your Device Code on the Square Dashboard. Once you're signed into your account, select Account & Settings > Business > Devices. From here you can view the device codes for all of your Square apps.
If you're using Square Point of Sale you can create a new Device Code by following the steps in this article: https://squareup.com/help/us/en/article/5586
For sellers using Square for Retail, please view the steps in this article: https://squareup.com/help/us/en/article/6349-set-up-your-point-of-sale-with-square-for-retail
For sellers using Square for Restaurants, please view the steps in this article: https://squareup.com/help/us/en/article/6390