when most of your black employees leave because of what they feel is racism in the workplace that’s harder to ignore
They weren't ignoring it. Some of these people weren't even saying they felt that way to Coinbase - one of the people who claims she was bullied also claims nobody told her how to make an official complaint and that's why Coinbase have no record of her views. Complaining to HR has to be the easiest task in any modern corporation; if she couldn't figure out how to do even that then we probably found the explanation for why she felt unappreciated: maybe she just sucked. Or maybe she's made up this supposed racism after she left, as part of achieving other ends (like getting in the NYT).
That is extremely vague. Is it a red flag? Yes. Does it imply racism? No. It doesn't even guarantee there is a problem or a systemic trend for that matter.
If there are 3 red flags and some actual evidence of racism then that is one thing. But there isn't. Even the number of black people quitting - what is the expected retention rate in that team? Most people quit due to dodgy managers, so people quitting points to a dodgy manager before it points to racism.
We know that Alysa Butler felt unappreciated. I'm hesitant to believe the NYT is even representing her opinions fairly. If you read what they've written about carefully, the article doesn't have her accusing Coinbase of any sort of racism, the NYT is just weaving her experience into a story that they construct elsewhere (normal practice in newspapers). A 'diversity problem' is different from racism. 25 year olds being ignored in meetings is not a new phenomenon either in my experience.
Yeah, I am completely ignoring that. "My presence in the workplace was excessively celebrated" isn't a complaint. There is nothing there to respond to.
If you want to argue that could technically be racist behaviour I agree, but typically when people talk about racism they are actually going to serious issues like money, power or personal safety. Photos taken for promotional material is not something that needs a defence - it is a frivolous thing to argue about. Any company might do that.