Linkedin was particularly annoying with the "you are missing out a lot ... a lot has happened since ..." type of emails. It would also give me couple of non-existent new notifications ... abusing the red indicator badges
I think the most egregious instance of this I have seen is the allegation that Facebook displayed fake notification badges during the GDPR flow, which pressures users into quickly accepting the terms so that they can see the notifications: https://www.dailydot.com/debug/facebook-gdpr-notification-la...
Yikes.