Once you upgrade from $69.99 monthly subscription to $99.99 monthly subscription you can not go back. The only way is to cancel your subscription and then re-sign back up with FUBO tv directly. You lose all you saved channels, movies and data. No downgrading options are available... only upgrading.
Not sure if this is the case with all channels, but is true of Fubo tv as of 1/26/2023.