The typical cloud-based nvr user doesn't care about control, otherwise no that stuff wouldn't sell. But when it comes to content, everyone has a problem when it ends up with strangers. Almost every second incident concerns the camera's push/notification function. Like this actual issue with NetAtmo , the have a similar issue like ubnt:
Unerwünschte Einblicke: Fataler Fehler bei Netatmo-Sicherheitskameras (in german).
Sure, these services have a simple transport encryption for the traffic and call it "end2end ecrypted". If the cloud service screws up, the wrong recipient gets the data and is able to read it. Similar things can happen if your mobile provider screw up (sim swapping,..). And of course there is no question that the risk is much greater with cloud nvr's. The risk of a privacy disaster is far greater with these cloud nvr solutions than the manageable risk of a few messenger notifications reaching the wrong recipient.
In the end, everyone should always be aware - shit happens. If you use any nvr cloud connectors, cloud based nvr's or even messenger services, there is a residual risk that the data gets into the wrong hands. In my opinion, there is nothing to be said against using telegram/pushover/whatever. If sombody has privacy concerns, simply deactivate the notifications for "private" areas when you are present. This is quite easy to configure, especially with BI. Some already play around with a privacy filter in frigate and blur naked body´s down the head or send the notification without picture if they detect a naked person.