ion is
made in order for all unit names to also be suitable as file names. If a mount
point appears that — after escaping — is longer than this limit it cannot be
mapped to a unit. In this case systemd will refrain from synthesizing a unit
and cannot be used to manage the mount point. It will not appear in the service
manager's unit table and thus also not be torn down safely and automatically at
system shutdown.

It is generally recommended to avoid such overly long mount point paths, or —
if used anyway – manage them independently of systemd, i.e. establish them as
well as tear them down automatically at system shutdown by other software.