I have tried all the suggested methods of stopping the auto backup of my files, but none of them work. So I have deleted my Murena account until I hear this has been fixed. The email and this forum still seem to be logged in, so maybe I will get a response here.
I do not need my music or photos backed up, they are backed up on a separate device.
Without specifics it is hard to know exactly what you tried. You should be able to turn off all sync to murena via Settings app, Accounts.
If you tried this and it doesn’t work, I guess this is an error that needs fixing.