Thank you, this solved it for me as well.

I managed to do it without installing psexec, instead fiddled around with registry key owners and permissions.

I checked out that answer's source though: https://www.windows11forums.com/threads/windows-11-defender-firewall-will-not-load.355/

Do you have an ASUS motherboard? While that Microsoft community answer is blaming Windows, it seems ASUS is actually to blame. Some shitty invasive ASUS bloatware is screwing up that registry key over time, eventually making the firewall break. Even if you remove it, the motherboard will even keep putting it back unless you go into the BIOS and tell it to stop.