Well I told you it could be insecure.
is the folder for full backup.
So you would only need to move that folder I guess.
Did you stop and restart LXD?
Try the following (to revert what you did):
- Stop LXD (also daemon)
- Remove the link (only the link, not the target folder!)
- rename /var/snap/lxd_legacy_20200509 back to /var/snap/lxd
- Try to move all data back to /var/snap/lxd
- Restart LXD
This should revert everything.
If LXD then starts sucessful again, you can just leave it as it is.
If you are in doubt, wait for a better answer, maybe by @stgraber or some of the other devs.
Sry for your problems, but I warned you .
I will look at it again tomorrow.