How does reddit maintain visit history after clearing cache, cookies and de-fingerprinting?
Setup: I clear cache and history in firefox, then visit reddit.com in a private window and browse/read three very specific subreddits while NOT logged in. Then, I close that private window entirely and re-open a new one. When I visit reddit.com, I see "recently visited" on the left margin - reddit has remembered those three subreddits in the margin.
That's troubling because why would different private mode sessions persist identifiers but, whatever ...
So I clear ALL cache and cookies.
I open up reddit - again in a new private window - and reddit still remembers those subreddits in the left margin.
So I clear all cache and cookies AGAIN and I go into about:settings and get aggressive with the anti-fingerprinting tunables - privacy.fingerprintingProtection and privacy.resistFingerprinting both set to TRUE, as well as privacy.resistFingerprinting.randomization.enabled and privacy.resistFingerprinting.testing.setTZtoUTC.
... and reddit still has persistent memory of previous visits and shows me previously visited subreddits in left margin.
I have a decent understanding of browser fingerprinting - I don't need a basic tutorial.
What I wonder is, very specifically:
What is reddit, specifically, employing to be this persistent ?
What might I do (firefox, macOS) to defeat their specific measures ?
FWIW this does not work in Safari - reddit cannot persistently ID me like this with Safari and I have made no special modifications or preference settings.
