Retire the iOS 9.3.5 device as a dedicated music player (Apple Music via Safari), a photo frame, or a classic game emulator. Let YouTube rest in peace on that hardware.
The experience is broken. You will spend 3 hours sideloading a repack only to watch 4 minutes of a video before it crashes.
Around late 2022, Google officially shut down the legacy YouTube app for iOS 9. Users were greeted with the dreaded "Error: Update Required" or a blank black screen. This led to a desperate search for a solution, giving birth to the search term: