https://arstechnica.com/gaming/2021/09/riot-games-anti-cheat-software-will-require-tpm-secure-boot-on-windows-11/

We already know that Windows 11 will officially require a TPM 2.0 module and Secure Boot support for installation when the operating system is released on October 5, but it looks like Riot Games' Vanguard anti-cheat software will be getting in on the fun, too. Users running Vanguard on Windows 11 systems have seen pop-ups notifying them that a TPM 2.0 module and Secure Boot support will both need to be present and enabled before Vanguard-protected games like Valorant will run on a Windows 11 PC. PCGamer reports that those requirements do not appear to apply to Windows 10 users, at least not yet (any Windows 10 system bought or built within the last five years or so will usually include TPM 2.0 and Secure Boot support, though one or both may be disabled by default).

Vanguard is already notable for the low-level access it has to your system—it uses a kernel-mode driver that launches when Windows boots, whether you're playing a game that requires it or not. Shut down Vanguard for any reason, and you need to reboot Windows before you can launch a protected game. Services like Easy Anti-Cheat also advertise kernel-level protection.