In my case (Cruise) I got offer once a quarter to liquidate any number of my vested RSUs at a price set by some third party assessor (roughly equal to last round’s valuation). If you sell the stock and get cash in your brokerage - amount needed to cover taxes. So basically like regular rsus except price is static

More info (although I personally didn’t use cart for this): https://carta.com/blog/tender-offer-faq/#