Link to the actual Consumer Reports report: https://www.consumerreports.org/electronics/privacy/each-fac... So most of the data provided is probably coming in via the FB tracking pixel. I think the references to FB's "custom audiences" is a red herring - it's a very manual process and very few companies use that feature in any sort of scale. FB hashes the data that gets uploaded and specifically throws out extraneous…
I guess FB tracking pixels will no longer work when third-party cookies are removed from browsers. That seems like a massive hit for them if I understand it correctly (and a big W for us)
Getting rid of third-party support will mean FB doesn't get anonymous data from random website users - but if you are logged into FB or hit the page from a FB link, it would still be trackable as a first-party cookie.