iCloud backup option is not swiping on or off its stuck on & it won’t let me backup

Did you go through the steps in the related article?

If you can't back up to iCloud - Apple Support

Do you have a profile installed that prevents you from backing up to iCloud?

Try a forced restart and see if that frees up the button to backup.

Force restart iPhone - Apple Support

Plug your phone into a wall socket to charge and connect to a WiFi network. Then see if it will backup.

And turn off low power mode!