Accessing LXD has traditionally required and granted a lot of privileges.
Effectively making anyone who could interact with LXD a full local administrator.

This isn't very compatible to restricted or multiuser systems where a specific user shouldn't be able to elevate their privileges and take over the entire system.

With LXD 4.22, LXD introduced a new user daemon which allows for two level of LXD interactions, the traditional complete LXD access granted to system administrators and a new, much more restricted kind of access suitable to regular users.

Such users get an automatically generated LXD projects allowing them to run their own (unprivileged) containers and virtualmachines, isolated from anyone else's instances and sufficiently restricted to prevent privilege escalation.

RESOURCES:
Blog: https://ubuntu.com/blog/shareddevelo...
Forum post: https://discourse.ubuntu.com/t/easym...
LXD projects: https://documentation.ubuntu.com/lxd/...
Website: https://ubuntu.com/lxd
Community forum: https://discourse.ubuntu.com/c/lxd/