Shortly after announcing Windows 11’s October 5 release date, Microsoft began booting Windows Insider preview PCs with unsupported hardware out of Windows 11 testing. PCWorld reports:
[T]he day that Microsoft announced Windows 11’s release date, Windows Insiders on unsupported PCs began receiving a message telling them they’re no longer eligible for the Windows 11 Insider program, as seen in BetaWiki’s tweet above and confirmed by BleepingComputer. Unsupported Insider PCs need to go back to Windows 10 to continue participating in the program (and presumably continue to receive updates). While the move isn’t a surprise, the timing is, as Microsoft previously stated that Windows Insiders with non-compatible hardware would be able to continue to run Windows 11 until it was “generally available.” Most PCs released or built over the last three years will run Windows 11 without issue, however.