They did get new investment (the story isn't clear if it's a bridge loan or equity)
https://techcrunch.com/2021/01/29/robinhood-raises-1b-after-...
https://techcrunch.com/2021/01/29/robinhood-raises-1b-after-...
"Investors who provide new financing to Robinhood will receive additional equity in the company. The investors will get that equity at a discounted valuation tied to the price of Robinhood shares when the company goes public, two of the people said."
https://www.nytimes.com/2021/01/29/technology/robinhood-fund...