OK, when I click on your System requirements, it does NOT list Windows 11 but if you are stating the MINIMUM requirements for QB Desktop 2021 has to have at least Windows 10, then that makes sense. I was confused because when you search in your community threads regarding this issue, it notes QB is aware of the incompatibility issues with Windows 11 and that your team was working on a resolution (reference: AbegailS_ QuickBooks Team ‎February 09, 2023 06:44 PM, Thanks for getting back to us, @PEStaffing.  Currently, we're unable to provide a specific timeframe when this will be implemented. Rest assured Intuit is working to ensure QuickBooks Desktop 2021 products will work as designed with Windows 11. We intend to complete the compatibility certification process soon. It may take some time because our engineers are making sure there will be no problem in the long run). 

Then a more recent post from JorgetteG, QuickBooks Team (‎June 07, 2024 08:08 AM. Every penny is important when running a business, SteveB100. I want to share some important information with you regarding QuickBooks Desktop and its compatibility with Windows 11.  You're correct that Windows 11 is not compatible with QuickBooks Desktop (QBDT) 2021 and older versions….)

So you are stating that QB has completed their compatibility certification process recently and Windows 11 can now run QB Desktop 2021 effectively?  We will take your instruction and download the installer on our computer and restore our qbw files.