Fitbit app not syncing with iPhone after upgrading to iOS 13.1? Here’s the fix

If you use a Fitbit, you may have noticed that the Fitbit app on an iPhone upgraded to iOS 13.1 will not sync with your Fitbit, complaining of a lack of Bluetooth connectivity, even though Bluetooth is on and the Fitbit is connected in Settings.
Turning off Bluetooth and turning it back on, reconnecting the Fitbit, restarting the iPhone… all three of the most common steps to reestablish a connection fail.
Don’t fret, there is a fix: Delete the Fitbit app from you iPhone and reinstal