[sayhar]

How could they tell you were on that subreddit? Presumably you were doing it from a separate browser on the phone -- can they really snoop on behavior in completely separate apps?

[derkades]

Indeed they shouldn't be able to know that without deliberately bypassing the phone's security features using vulnerabilities. Maybe confirmation bias is at play here?

[ncpa-cpl]

I guess it could be the same IPv6 address, or IPv4 + user agent matching with a third party ad categorization service.

[ncpa-cpl]

> How could they tell you were on that subreddit? Presumably you were doing it from a separate browser on the phone -- can they really snoop on behavior in completely separate apps?

The subreddit was opened in an incognito window, and the native app on the same phone.