E.g. a phone dialer app that asks if you want to dial the number in the clipboard when you start it, an image editor that asks if I want to create a new image size the dimensions of the clipboard, a torrenting program that when I choose to import a torrent automatically grabs it from the clipboard before I even get the choice to pick another option (though I still can).
I would be very surprised if this wasn't originally part of something like that, and maybe the feature was removed but the detection function wasn't.
Because if we put down our pitchforks for a second, LinkedIn is owned by Microsoft, which also owns a major browser and the world's most popular operating system. Microsoft sure as hell doesn't need to sniff your clipboard in LinkedIn, if it wanted to do something for nefarious purposes.
Never attribute to malice that which is adequately explained by stupidity.