Can’t delete snapshot

Hi there, liking more and more Kopia, I’m extending it to an S3 bucket. I need to delete a snapshot from my old B2 bucket but it fails. It says invalid object ID, and Malformed content id.
Not sure I provide the correct ID. Are they those you get with « snapshot list » ?
What is the right command to delete ? kopia snapshot delete —delete ID ?
Thanks in advance