Comment by holowoodman

seccomp BPF, eBPF, in a way SELinux/AppArmor/Tomoyo/..., maybe you can even call namespaces some kind of syscall filter. And then there is the auditing framework, where you can at least record which critical syscalls were performed.

Nowadays its mostly a combination of eBPF, SELinux and auditd plus namespaces in case of containers. Usually in the combination that some distro ships, so nothing really fancy.