Rule #n of the internet: If Meta does anything which doesn't explicitly protect the privacy of users, you can safely assume that it harms the privacy of users.

I went to Vice's fb page, found the same post that OP linked to and checked the URL. The pfbid part is exactly the same to me. The URL by default has some additional params attached like __cft__ and __tn__, which can be stripped, and those are probably tracking-related. Based on this, I don't think that pfbid is connected to tracking

If I were Meta, this is how I would implement this. First, get everyone used to the new opaque base64 encoded blob, by using it just like the previous numeric post id. Then, after all the initial speculation dies down, encode other stuff in it.

Are you sure about that? It's not the same for me.

OP: https://www.facebook.com/VICE/posts/pfbid02XdVziPTwhmPU9XzBq...

Me: https://www.facebook.com/VICE/posts/pfbid0TbuHEaGP2fLTRDFRTu...

There were also a bunch of other query params junk after that I omitted here for brevity.

Facebook will Facebook, that's a given. But why aren't FB employees (anonymously) responding here and explaining how this "pfbid" thing can be circumvented or even what it contains? Where are the actual privacy activists that will do a grep through the FB sourcecode for pfbid and give us the scoop??

It looks like one already explained what this is: https://news.ycombinator.com/item?id=32119684

probably takes a certain mentality to still be working at facebook and the people who cared enough to do this sort of thing left instead

Multiple other companies doing the same thing would point to a trend.

what's the reason to change from the old format if that's all it does?