Having worked at meta, something I noticed is that the orgs that were well run were ones that were bought. WhatsApp, reality, insta, etc. I worked in an org that was not associated with those products and was purely homegrown and it was awful. Things got done but horribly inefficiently due to over hiring and extreme requirement and schedule shifts.

I believe that the cultures that were developed outside of Meta are used to launder the image that meta as a whole has a good engineering culture.

I had a similar experience at Google, they were so convinced they were the only good engineering company in the world and had to protect themselves from all the wrong-thinkers outside and yet the only progress they made was via acquisitions.

I had a friend who worked for Instagram post-acquisition left and came back to a team in Facebook.

They had always sung the praises of Instagram's culture but said they didn't recognize the company that they came back to. Literally night and day between the best and worst place they'd worked.