0 byte ingress, egress 10GB after large deletion

Hmmm. I wonder if your issue is related to this:

I see a bunch more trash got dumped since your last post. Are you sure you typed df -H with a capital H? Because 646 GiB = 639 GB, which is the exact amount your node is reporting as free. Which is a “symptom” of that bug. I am leaning towards this as being the problem.