Comment 14 for bug 1821625

$ reverse-depends -l -r bionic -b libseccomp-dev |& xargs
apt chrony docker.io flatpak gnome-desktop3
golang-github-seccomp-libseccomp-golang kscreenlocker lxc man-db ocserv
qemu snapd stenographer systemd tor tracker-miners usbguard

none of those packages reference pkey_mprotect except systemd, qemu, and snapd; systemd and qemu are discussed above. The snapd package simply lists pkey_mprotect in a list of syscalls and doesn't appear to compile-in the syscall number, and so should not be affected:
ddstreet@thorin:~/bugs/lp1821625/sym-check/snapd/snapd-2.39.2+18.04$ grep -r pkey_mprotect
cmd/snap-seccomp/syscalls/syscalls.go: "pkey_mprotect",

additionally, snapd is updated quite often, so even if it is affected there should be no need for a no-change rebuild.