But if I just delete the existing fly I think all my waypoint missions will be deleted, which I definitely don't want to do. It's interesting that my current fly version is 1.19. But softonic only has these: I can't find my screenshot. Maybe later.
No need to roll back ,Simply Delete the existing Fly and then go to APK mirror and select the version you want to use.
Remember to clear your cache or the new install won't work!