Secure boot and TPM aren’t known for there robust security. In fact, I’d wager that your machine is probably vulnerable.

https://www.bleepingcomputer.com/news/security/bootkitty-uefi-malware-exploits-logofail-to-infect-linux-systems/

Or for that matter, it is possible that your secure boot keys have been leaked or that your TPM is vulnerable to sniffing.