"Required tool 'zpool' is missing", but it's not

I’m trying to add 2 more nodes to my LXD cluster, but get:

Error: Failed to join cluster: Failed to initialize member: Failed to initialize storage pools and networks: Failed to create storage pool 'local': Required tool 'zpool' is missing

But zpool is NOT missing:

which zpool

What’s wrong?
How to solve it?

Is that with the LXD snap?

If so, can you show modinfo zfs?