[dilliwal]

I did the same for many years, blocking third party cookies, having a different browser profile, but none matters.

Recently I downloaded all my fb data and I found that fb gives a tool to advertisers where they can upload my contact information to join all the dots.

The heading says "Advertisers who uploaded a contact list with your info"

https://imgur.com/a/FRsUP

[Antrikshy]

That's kinda the opposite. The brands somehow had your info (from accounts you may have created with them, for instance), which they explicitly imported into Facebook specifically to show ads to you etc.

[dilliwal]

Yes, it seems like that, and thats what I am trying to say, that browsers are just one vector, users information is collected from number of sources: - apps you use on your mobile - your email/phone (example: which you gave to a Pizza company is same as of your fb) - Your address which is with a local store nearby etc. etc.

All this information is collected to connect all the dots.

When I was going through the advertiser list, I was kinda shocked coz I never give my any detail to them, and still they have somehow uploaded it to fb. FB should ask the advertisers about source of data.