Comment 16 for bug 1989019

As for the shared propagation default, that's a systemd choice and snapd is not altering that. As for your comment on mounting I think you misunderstand how this works. Sadly read only flag is a bit more confusing as there's one on the file system and then there's a separate one on each mount point where that file system shows up (bind mount).

In both cases /home is not read only. In fact, it was not bind mounted by systemd but by the kernel due to the propagation. I agree this is non-obvious and difficult to reason about somehow but those are both external to snapd.

I would try to focus on:

1) Determining how your fstab was modified
2) Adding precautions to snapd to detect something of this sort to avoid data loss.