There is loads of information here on some of the issues with the Fly app
You can uninstall the current version and install an older version but you will need to turn off auto-updates in the app and in the phone settings, most have gone back to 1.4.0 or 1.4.2
There is a beta version of the troubled latest on trial, but I haven’t tested it yet… 1.4.8 (1185)
You can download it and the others from here:
https://drive.google.com/drive/folders/1No6Y6900jugASpW_LB7UDL6GevH4WVg5