It was Megan Kacholia, who had put Timnit Gebru and others close to her down for a long time constantly within Google, always talking down and being condescending and rude, failing to respect Timnit in how she confronted Timnit about the paper (which she was ordered to retract by way of not Google's normal paper review process, but by a then-newly-implemented and since retracted secondary "sensitive topics review" process, due to a combination of actual mistakes like the environment numbers, and also Google being too afraid of reputational damage for her discussion of the very real and tangible harms of LLMs).
Timnit tried to raise this to Jeff Dean to get help (Jeff was Megan's manager at the time). Jeff completely misunderstood what she was asking for, and instead sent some response about the environment numbers being incorrect (and they are, but that doesn't at all justify the way Timnit was treated). Not beginning to imagine that Jeff could have missed this signal, Timnit responded sarcastically. Jeff didn't pick up on the sarcasm and thought all was good.
Timnit then reacted by describing her frustrations with how she was treated in an internal diversity mailing list. She also emailed Megan Kacholia with a number of demands, mostly to be treated reasonably. Appalled at how she and her coauthors were treated, she refused to retract the paper. Megan reacted by taking her note that she would work on a resignation date if demands were not met in combination with Timnit's email completely pedantically and out of context, using them as an excuse to fire her by rushing her out, without allowing her to follow the actual resignation process. She also acted over Timnit's manager's head (Samy Bengio), who was so annoyed he later quit. (Megan cc'd Jeff, but hadn't spoken to Jeff about any of this, and was acting on her own.)
Interestingly, Timnit's email to the diversity list was so resonant that several of the changes it asked for in how Google approaches diversity were enacted after her firing. But Megan and Google's official line on all of this chose to obsess over Timnit's rhetorical devices and take them literally instead, using an email to a diversity list about diversity against her. People are still too afraid to talk about diversity on diversity lists, now, because of Google using that email against her.
Google reacted by gaslighting Timnit to protect its ass. After Timnit Tweeted that Jeff had fired her (Timnit probably really thought that Jeff and Megan had spoken to each other before Megan had sent that email), Jeff participated in this part in public, on Twitter, with a lot of serious consequences for Timnit and others, without considering power dynamics. (Jeff suffered a lot on Twitter, too, but that doesn't excuse not considering power dynamics in such a consequential way on such a consequential medium.) Timnit and others, including me, were harassed and threatened because of this, by way of third-party harassers. I was not even involved on the paper, just proximal damage. I was afraid for my life honestly.
Meg Mitchell, feeling lost, having seen the truth of how Timnit was treated internally, and trusting Jeff to protect her, tried to put together some things for Jeff to get him to see how Timnit was mistreated. She panicked and backed them up on her personal email because she was afraid of retaliation from Google (a reasonable fear---doing any diversity or community work at Google that at all challenges the status quo IME gets you retaliatorily reported to PeopleOps, who then try to get you in trouble and read your private communications and so on). She was transparent about doing this and gave instructions for Google to remove her personal copy if needed. Sundar Pichai fired her and then comms smeared her publicly with outright lies. She was harassed and threatened for this, too, and a number of places refused to hire her because of Google's treatment of her. Really tangible damage emotionally, financially, and reputationally.
Out of fear of being sued, Google's comms and legal departments reacted by continuing to censor and gaslight. Sundar was extremely complicit in this, too. Megan was moved out of Research, but not much else happened; she continues to send monthly emails about diversity, as if her continued contact with Research is not actively harmful to diversity.
So sick of internet people speculating about this without knowing anything about the situation. Sorry if I broke anyone's trust here. Just can't deal with this incorrect speculation anymore. (I have extremely thorough information about this, but to those directly involved, please feel free to correct me about any details I got wrong, or about important details I omitted.)