I don’t remember well why mount bind is better, i think it’s due to the way yunohost backup the file and also how some apps could be disturb by symlinks.
I am not sure symlink target are added in backup list (or maybe they are not correctly added so restore an app could crash due to that. It’s possiblke it create unoptimize things and need a lot of more available space on the origin system to backup it.
I think you can just delete the symlink and mount bind (and add the info into fstab to be sure the mount bind will be done at boot).