Ubuntu 20.04 zfs grub rollback snapshots

I’m interested in teh ZFS snapshot feature, So I deployed 20.04 VM with ZFS.
I created a snapshot to test how the rollback procedure works.

sudo snapshot -r rpool@SNAP1

When then I created and deleted a few test files.

I rebooted to grub went to histroy, selected my snapshot.

Booted into Ubuntu, and nothing has changed, the files I deleted are still deleted and the files I copied after the snapshot are still copied.
My understanding is rolling back to a snapshot would bring the filesystem to the state at the time the snapshot was created.

So I did some more testing, added and deleted some files, created a new snapshot

sudo snapshot -r rpool@SNAP2

rebooted to Grub menu, went to history, now, I do not see my latest snapshot, the first one is still there, but not the new one.

So I went in Ubuntu and destroyed the first snapshot and rebooted to grub, just to find the first snapshot is still listed in the grub history menu..

Am I missing something ?