Facebook (Meta) deployed VPN spyware with Onavo (ref) (a startup they acquired, whose CEO is now in charge of “chief information security officer” at Meta… go figure). Apparently, usage/tracking data from Onavo helped Facebook justify the rather high acquisition costs for Instagram ($1b) & WhatsApp ($22b).
In fact, the visceral disgust I have for spyware like Onavo is why I put so much time & effort in my current project!