Comment 5 for bug 1989019

Normally /var/lib/snapd/hostfs is not mounted in the initial mount namespace. It is only visible from the mount namespace of individual snap processes. Can you run /lib/systemd/system-generators/systemd-fstab-generator and provide the output it generates? Can you also share your /etc/fstab in case there is something special there?

To be clear: if you see /var/lib/snapd/hostfs mounted, then something is extremely wrong.