I've got a Samsung Galaxy J3 Prime running Oreo 8.1 that is getting NET::ERR_CERT_AUTHORITY_INVALID on literally every website, regardless of browser. When I check the security certificates (Settings -> Security -> Other Security Settings -> View Security Settings) I see that every certificate is disabled and if I try to enable them they seems to disable again immediately.
I've tried multiple networks and applied all the updates I can with no luck. This is a friend's phone so I don't know if any apps have been installed recently or anything.
Hopefully someone can think of something I have not.