Twitter had a FUBAR IT department seriously lacking in fundamentals. Children and criminals were running the IT division of Twitter. 5000+ people had access to live production data/environment. They didn’t even have dev and QA servers or testing data. Developers did their changes DIRECTLY IN PRODUCTION!
Great thread here about it:
https://twitter.com/AvidHalaby/status/1602127460677844993
Twitter Whistleblower Disclosure
https://s3.documentcloud.org/documents/22186683/twitter-whistleblower-disclosure.pdf