I'm having this same issue. I manually installed the patch (as described in earlier posts):
https://ttlc.intuit.com/community/updating/help/manually-update-turbotax-for-windows-soft[product ke...
As soon as I run TT, it wants to do another update. I agree to the update and it fails:
"Failed to install update. Microsoft Installer error: 1603, Fatal error during installation"
(Released 3/4/2021) Program Updates
