Proxmox guest stateful snapshots and disc consumption

So I understand how ZFS snapshots work, and why they consume no disc space (initially), but I’m struggling to find any information on why stateful (with memory) snapshots consume so much space.
EG: guest has 8GB ram allocated, 3GB active, and a 32GB disc. I do a stateful snapshot which claims 3.07GB ram in the snapshot, but the resulting snapshot is 17.07GB. This is immediate, not after shuffling a bunch of data around. This is dead consistent as well. This particular guest always consumes 17.07GB, while another one which should only be consuming around 1GB (the contents of active RAM), consumes 14.5GB for every snapshot.

Needless to say, filling up a 10TB volume doesn’t take long. I almost ran outta space over the weekend with only a handful of running guests, by taking bi-hourly snapshots (with 23x retention) and daily snaps with 6x retention.

What’s going on here? Where is this space being consumed? Every method I’ve used to investigate the snapshot claims theyse should be 3GB and 1GB respectively. IE: roughly the size of the active RAM.