Thank you. I actually got an email today (screenshot below, with email address obscured for the account that was already opted out).
I have also checked notification settings in the Plex android app for the same account as you suggested and emails are disabled, as expected.
I think this is expected behaviour. I used the unsubscribe link at the bottom of the Discover Together Week in Review email last week to unsubscribe, expecting this to populate across my account, regardless of any other places that may show the same settings, e.g. in the app as you have pointed out. This appears to be behaving correctly, and showing as already disabled in the app too.
