the part about scanning for 509 job search extensions is especially nasty. imagine getting flagged to your employer because linkedin detected you had a job board extension installed.
It is pretty easy to signal stuff on linkedin without intending to do so. For example whenever I get an old coworker adding me on linkedin, they are 100% of the time job seeking. Inevitably they start a new role some weeks later.
All one has to do is just measure employees linkedin activity. I mean truthfully people don’t use the site at all if they aren’t actively looking for work. It is corporate dystopia otherwise. It is trivial to find these signals.
Several years ago I heard the company I worked for say they had a way to get notified if it seemed like an employee might be thinking of leaving, so they could take some kind of action. I now wonder if LinkedIn, or various job sites, were selling them data.