It appears every few times I open the app and the usual android back button doesn’t make it go away, and there is no cancel button. What you have to do is toggle the toggle, then the button will change to “do not back up” and then you can press it. It annoys me how easy this makes it to accidentally turn on backup.
I recently picked up an iPhone as a secondary device, pretty much immediately disabled iCloud and installed Mobius (Syncthing) so the photos get sync’ed over to my fairphone’s SD card.
Now i’m second guessing whether it’s actually disabled, or if I’m going to get an iCloud full warning in a couple of months…