How can I get a sense of the usage of my ephemeral-storage usage and if my config is working?

I've been having several issue on my pods getting evicted due to ephemeral-storage. I just created a ResourceQuota to try to increase this and it looks like this.

# For volumes that use emptyDir
apiVersion: v1
kind: ResourceQuota
metadata:
  name: compute-resources
spec:
  hard:
    requests.ephemeral-storage: 2Gi
    limits.ephemeral-storage: 4Gi

My pods have 2 containers inside each as they share a mounted volume of type "emptyDir". When I sh into them and run "df -h /var/lib" I see.

overlay                   5.7G      5.1G    600.3M  90% /

I can't seem to wrap my head acount that ephmeral-storage. Where exactly is this thing how can I monitor it? I saw by default it's stored in memory of the pod?