It could be some kind of 'target blank' attack, if you have Gmail open in one tab then open a link from a linkedin email onto their site, they have access to your gmail window and can probably get your contacts.

Couple of examples explaining it better than I can: https://dev.to/ben/the-targetblank-vulnerability-by-example https://www.jitbit.com/alexblog/256-targetblank---the-most-u...