Niels, you are correct about my initial tweet, which I updated in later tweets to clarify with a hat tip to Will Hargrave as thanks for seeking more detail.

Cheers,
Ryan

On Tue, Oct 5, 2021 at 08:24 Niels Bakker <niels=nanog@bakker.net> wrote:
* telescope40@gmail.com (Lou D) [Tue 05 Oct 2021, 15:12 CEST]:
>Facebook stopped announcing the vast majority of their IP space to
>the DFZ during this.

People keep repeating this but I don't think it's true.

It's probably based on this tweet:
https://twitter.com/ryan505/status/1445118376339140618

but that's an aggregate adding up prefix counts from many sessions.
The total number of hosts covered by those announcements didn't vary
by nearly as much, since to a significant extent it were more specifics
(/24) of larger prefixes (e.g. /17) that disappeared, while those /17s
stayed.

(There were no covering prefixes for WhatsApp's NS addresses so those
were completely unreachable from the DFZ.)


        -- Niels.