pg_dump. Some COPY processes stuck on 'idle in transaction' after pg_dump completion
It is slightly surprising that pg_dump returned sucessfully with a return code of 0. The only theory I can come up with is that some of the 10 jobs got done early and started to idle, whereupon a misconfigured firewall cut the connection. The backends should die after around 2 hours due to TCP keepalive.
What you could do is reduce the keepalive idle time and see if that improves things:
pg_dump -d 'host=... port=... dbname=... user=... keepalives_idle=300' -f dumpfile