I joined the Windows Insider Program months ago, and I currently have Windows 11 activated. For some unknown reason, I have this on my screen, but I know as a matter of fact that this is false. I know that Windows 11 is officially released now, but this is not the kind of message that should be displayed here if the Windows Insider Program is obsolete now.
When Windows 11 Insider program was available, Microsoft didn't enforce all requirements and now that Windows 11 released to the public these requirements are being enforces and this might be a correct message. You may run the PC Health Check app to see if your device meet the requirements or not. Take a look at: https://www.microsoft.com/en-us/windows/windows-11#pchealthcheck