[RegW]

In Antonio Garcia Martinez's 2016 book "Chaos Monkeys: Inside the Silicon Valley Money Machine", he talks about a deal done between Google and Facebook to exchange data. So I'm pretty sure that would be happening.

Not so sure about Facebook analyzing your WhatsApp traffic, because they make such a big thing in their advertising about the secure end-to-end encryption and privacy. Surely they would get roasted if it was found not to be true. Of course it's always possible with a closed source app.

The technique discussed in Darknet Diaries episode 146 (about the ANOM phone) involved duplicating the message to [an] archive endpoint. It mentions Google providing text archival as a service for company phones, and it seems this also happens for WhatsApp. However, are Facebook also purloining your private WhatsApps? Are they using them to target you? Who can say?

https://www.waterstones.com/book/chaos-monkeys/antonio-garci...

https://darknetdiaries.com/transcript/146/

https://www.telemessage.com/mobile-archiver/whatsapp-archive...

[RegW]

On reflection, I think a more likely explanation is that Facebook just harvested, used and shared your WhatsApp metadata. Metadata analysis doesn't seem to count as an invasion of privacy in the modern world.

So while you and your friend chatted about this college, perhaps your friend googled it.

FB might then share with Google that you connected with your fiend at that particular time, and Google connected your exchange with the search.

Of course this assumes there is some way to tie your FB and Google accounts together - like matching up shared FB & Google tracker journeys across the internet.