Edit: The following is correct but misleading. The Muller report was reported to be released before the Facebook security update.

Facebook announced this before the Muller report was released.

The Facebook security post was updated April 18, 2019 at 7AM PT [1].

The Muller report was released "Thursday morning, shortly after 11 am [EDT]" [2]

[1] https://newsroom.fb.com/news/2019/03/keeping-passwords-secur...

[2] https://www.vox.com/2019/4/18/18411966/mueller-report-releas...

Disclosure: I work for a big tech company but not Facebook. All opinions are my own.