We have the same question. There are two links that show in the search results for this issue. However, they do not provide a solution. They only state that once you are complete with e-filing, the stamp will go away.
But if you are not e-filing, you are left without a solution.
Also, why would this stamp even be on the vouchers? It does not show up on the state vouchers. The estimated taxes are a result of user inputs that do not have to be cleared with the IRS, so why why why?
Hopefully someone at Intuit will respond.
The Form 1040-ES, Individual Estimated Tax is scheduled to be available on 02/18/2021
Go to this website for IRS forms availability - https://care-cdn.prodsupportsite.a.intuit.com/forms-availability/turbotax_fed_online_individual.html