Delete one specific snapshot (dependant clones problem)

Hey - I need some help & advice:
I have a snapshot, taken during an automated updated in October that has 124GB of trash (it is actually real trash from Nextcloud!) and it sits on my SSD-Pool which generally only has 124gb - which makes it even more annoying.

It is this one here:

I tried to delete it, but it claims to have dependant clones, which I’m unable to locate or delete.
I also tried this solution:

But it just says:

sudo zfs promote SSD-Pool/ix-apps/app_mounts/nextcloud/data

cannot promote 'SSD-Pool/ix-apps/app_mounts/nextcloud/data': not a cloned filesystem`

How can I get rid of this stuff?

I destroyed it with the -R option!
Just the GUI did not tell me to use it - but after searching for hours, I found how to do it within the shell!