I noticed “backup to iCloud” was switched on on my device. I don’t recall switching it on and wouldn’t do so intentionally.
Am I right in understanding that all of my documents which were previously only stored remotely in encrypted sync locations have now been handed over to Apple?
Are there steps to removing it besides just disabling the option?
If it is the case that all of a user’s data is exposed to Apple with that one button, please give a warning/alert. I see one in the “locations” settings, but that’s not where the problem would occur, where a user presses “backup to iCloud”.
My understanding is that the data was encrypted in transit and is also encrypted at rest in iCloud; it was not end-to-end encrypted though, and my understanding is that Apple has the key to the encryption used at rest.
As regards deleting the data from iCloud, it might be worth reading the instructions here and in the next section on the same site. Other sources seem to suggest the same steps.