Firefox rolled out Privacy Preserving Ad measurements (PPA). I originally posted my two cents about this on Reddit.

People completely misunderstand this feature (which is only a temporary prototype anyways), and I think that’s entirely Mozilla’s fault. They do a really poor job explaining it.

Usually ad networks implement sophisticated tracking, which works in a highly invasive way. They need the telemetry to watch their campaigns. Firefox now offers the option to collect a minimal amount of data for them and inform the network indirectly.

This is a good thing for the end user. The trackers are not needed, you gain privacy. Disabling the option makes it so you’re instantly tracked MORE.

Mozilla shouldn’t have staged this as an opt-out of the new system. You actually OPT-IN to networks running their old scripts on your machine to collect your telemetry:

[ ] Allow ad networks to run their own telemetry

(Beta functionality, some advertisers may still run their
own trackers, even when this option is disabled.)

That would be the same thing, but communicate what it’s doing.

The fact that advertisers like Meta might be on board with this should be exciting to people. That they are even considering giving up so much data and now only receive a single number of impressions per campaign is very unexpected.

Also, none of this matters if you block ads anyways. If you don’t load the ad, neither the networks script runs its telemetry, nor does Firefox increase the counter for the campaign id.

If you're wondering what's every involved party's gain in this, an interesting read is the IPA white paper, where the overall design targets for the system are stated:
Interoperable Private Attribution (IPA), 2022

In particular:

In designing IPA, we set out to find a win-win-win solution for cross platform attribution measurement that met our goals across privacy, utility, and competition.

Privacy: data collected about the user is minimized, protecting the end-users privacy.
Utility: the telemetry process is unified and simplified across all platforms, reducing the costs
Competition: it will be an open, standardized system, accessible to everyone

Just to be clear, I dislike the way Mozilla rolled this out. They already have a "Studies" checkmark that people can enable if they wish to participate in stuff like this. That Mozilla treats this prototype differently is actually not ok, and breaks trust with their users. But as far as I'm concerned, this is a completely separate topic from the update content, which I wish to be successful.

I recommend reading Andrew Moore's take on this, which is much more eloquent and knowledgeable. Jonah Aragon is much more critical about the topic and raises important issues. I particularly want to highlight his paragraph about the Uselessness of PPA.

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