The ZFS kernel module version needs to align with one of the versions of the tooling the LXD snap bundles, which from LXD 5.12 onwards (due to the switch to core22 base) is ZFS 0.8 and greater.
What distro/kernel version are you running?
For Ubuntu for instance, which bundles ZFS module, using the HWE kernel can get you a newer ZFS module.
For example on Ubuntu 18.04:
sudo apt-get install --install-recommends linux-generic-hwe-18.04
Alternatively you can switch back to LXD 5.11 temporarily using:
snap refresh lxd --channel=5.11/stable
to allow continued operation until you have upgraded ZFS.
Be aware that this means you will not get security or bug fix updates on this channel because LXD 5.11 is no longer supported.