To signal boost, because "lol proprietary services":

https://www.videogameschronicle.com/news/the-entirety-of-twitch-has-reportedly-been-leaked/
https://www.theverge.com/2021/10/6/22712250/twitch-hack-leak-data-streamer-revenue-steam-competitor
https://www.theverge.com/2021/10/6/22712365/twitch-data-leak-breach-security-confirmation-comments

I'll start reading this, but I'd be willing to bet this was some
process vulnerability when doing the ownership handoff between Twitch
and Amazon.