That's not how taxes on RSUs work (at least federally in the US). Nothing happens when RSUs are granted because they have no value until they vest. Once the RSUs vest, you are taxed based on the cost basis of $0 (since you pay nothing for RSUs).
Options on the other hand are a different beast.
https://arstechnica.com/tech-policy/2020/11/overpaid-executi...
as I understand it the value of the RSUs is on the _grant date_ for such purposes. (and not at vesting)