Not important and it won’t ‘break’ ssh. It might prevent login via ssh is a users home directory was under /data.

Only xfs filesystem is recommended for mongodb (data directory).

Please read further production notes in the manual.

Is this a brand new install or did you copy your existing database files into this directory, are there any files in the dbPath?

You could try the following:
sudo -u mongodb mongod -f /etc/mongod.conf --repair

And then see if it will start via systemctl.

Another possibility is incompatible permissions along the rest of the path, though I would expect a different error. Check that mongodb or ‘others’ have read and execute on /data /data/var /data/var/lib