[krn]

> but even that wouldn't solve the problem that all of our metadata is correlated, and nothing blocks first-party tracking

That's true – nothing stops Google from knowing what you were looking for – but if your girlfriend was seeing ads, she wasn't using uBlock: because it blocks all first-party ads, too.

I think a much bigger problem here is that almost nobody uses Firefox for Mobile. Also, uBlock doesn't block ads across native apps (for instance, YouTube).

The solution is to use something like NextDNS as your DNS provider at OS or router level. At least on Android 9+ and most latest Linux distributions (via systemd-resolved) no additional software is required for it to work.

[klyrs]

I don't see much of a difference between recommendations and ads, personally. And in this context, the distinction is moot. Ublock doesn't hide amazon recommendations, does it?

[krn]

That's a good point. But in such a case, it's neither cross-site tracking, nor ads. It's just Amazon's recommendations based on a shared IP address.

uBlock can be used to block both, "Sponsored" products, and Amazon's recommendations. But it won't help when using Amazon's native apps – which many people probably do.

You either have to use a VPN to hide your IP address (Mullvad seems to be trusted even by Mozilla), or at least switch to your mobile 4G/5G connection when doing anything more privacy sensitive.

[klyrs]

What stops Amazon from purchasing my data from my credit card company and other data brokers? Those recommendations are advertisements for products, and they are almost certainly informed by third-party data. You can't block cross-site tracking by any technological means when you're giving out your name, phone number, credit card, and home address -- you'd need to generate a whole new identity every time.

I agree that ublock, VPN, browser compartmentalization, etc are all really good practices. But they don't stop a first party from sharing everything they know about you, or embedding content derived from third-party brokers

[krn]

> Those recommendations are advertisements for products, and they are almost certainly informed by third-party data.

The initial example you gave was almost certainly informed by your browsing behaviour, because that's when those product recommendations started.

I agree, that it has become impossible to completely avoid being tracked, but there are many tools that can significantly reduce the data leakage.

In case of credit cards, that's what virtual disposable debit cards, such as from Privacy.com, are for. I personally never use my physical credit card for online purchases.