I am not 100% sure if my assumptions are correct, but I’ll give it a shot.
If you open system/mailtemplates the system will try to sync the mail templates referenced in the DB with the mail templates from the respective plugins (or your “app” etc.). I think this means that you have a refence to a mail template in your database, for which the actual view file is missing. Guessing from the name of the missing template, you might have used one of the Form plugins locally, but did not install that in your PROD setup.