This isn't the first time something like this has happened - her phone is not signed into iMessage, and to ensure Apple doesn't have access to her SMS / RCS, I've also disabled "Filter messages from unknown senders". Two times, over a period of roughly a year, I find that this feature has silently been enabled again.
Obviously, this sounds like a crazy rant, and that's how Apple gets away with it. (After all, it's just my word - how exactly can I prove this? And no, unless Apple is installing silent updates, this isn't happening during ios updates because I check the Settings with a fine comb after every update to see if Apple has reset it. When pushed, "bugs", ofcourse, will be the ready made excuse offered, just as they did when they broke all application firewalls, like Little Snitch, on macOS, to allow macOS and Apple programs to again silently contact and transfer information without the users knowledge.)
The way Android and ios (and even Windows and macOS) are designed today, Google, Apple and Microsoft can remotely access and control our devices. One would think that Mozilla's widespread abuse of its users by running silent "studies" on Firefox browser, without its users knowledge, would have lead to some real outrage and meaningful political action to prevent this behaviour (https://www.zdnet.com/article/privacy-touting-mozilla-caught... - https://www.zdnet.com/article/privacy-touting-mozilla-caught... ) ... Sigh.