@dmarti @thomholwerda According to Firefox the "ad measurement" feature in 128.0 is not generally available yet. It's locked behind this thing https://wiki.mozilla.org/Origin_Trials which means each site using the feature has to be individually approved. I don't know if Firefox publishes the lists of who's enabled for which origin trials. They assert the feature is only for "experiments" about whether the feature gathers useful data, but I'd be very curious if Facebook sites are among the ones "experimenting".