Have a look first at Comparing LXD vs. LXC and https://blog.simos.info/comparison-between-lxc-and-lxd/ (my post that summarizes the main points of this forum’s thread). These are about the differences between LXC and LXD.
You have installed LXD twice, as a deb package and as a snap package.
And most importantly, your containers are located in /var/snap/lxd/common/lxd/containers, which means that you have been using LXD from the snap package.
But it does not make sense though. Because if you have installed lxd-client (along with the snap package of lxd), then you get the utility /usr/bin/lxc from this deb package, and by default it masks the lxc from the snap package (/snap/bin/lxc).
It is likely that initially you only had the snap package of LXD, and it has been working great. For some reason, the deb package of LXD was installed, which brought in the deb package lxd-client that eventually masked the /snap/bin/lxc from the snap package (because it is later in the $PATH).
Therefore, to verify whether what I am saying is correct, run the following.
/snap/bin/lxc list
If you can see the list of your containers, then all is good.
Report back to get to the next step.