The Windows update compatibility check runs a scheduled task that runs periodically compared to PC Health Check App which shows information in real-time. So, if you turned on a requirement like TPM recently, the status in Windows update would take a while to change, so give it a day or two. If you cannot wait, update manually using the steps below:
Check Windows 11 compatibility
https://www.yourwindowsguide.com/2021/09/window...
Download Windows 11
https://www.microsoft.com/en-in/software-downlo...
Use the Installation Assistant to Download Windows 11
https://go.microsoft.com/fwlink/?linkid=2171764
Alternatively, download an ISO file and Run Setup.exe to Start the Upgrade, using Windows 11 Media Creation Tool.
https://go.microsoft.com/fwlink/?linkid=2156295
All steps, including MCT and Installation Assistant, are covered here:
https://www.yourwindowsguide.com/2021/10/instal...
Hope that helps.