How does lxc move detect that move was successful?

When I was dabbling a bit with CRIU/stateful migration I managed to completely destroy a container.
I was moving an ubuntu 18.04 container from a file backed storage (inside the lxd snap directory) to a zfs storage on the same machine.
The end result was an unusable container in the zpool and no container in the loopback storage.
I do not mind the the resulting container was unusable, but i did not manage to get my container filesystem. That was a simple test container, so no harm done, but I am a bit surprised that the original got deleted although the target does not come up.
How does lxc detect that the move was “successful”? Is there a flag to “delay” deletion?

I just realised that lxc move is probably just the lxd client command and not about LXC. I would guess that Incus has the same issue(?). So probably I should ask at the ubuntu LXD forum?

Move is copy+delete, the delete happens when the copy succeeds with no errors.

It’d be interesting to know exactly what state the destination was in as it’d be very unusual for the transfer to have actually lost data without failing.