Hacker News Reader

That's not really a thing. The pools are large-ish; the chances of winding back on the same IP after a change are tiny.

Not speaking for all ISPs worldwide.

Maybe running dynamic DNS client that keeps logs of IP address changes. Do DDNS clients keep logs. Maybe passive DNS would detect changes.

The point of the comment was that cannot just assume it never changed unless monitoring it contiuously.

Well if you don't notice it, for a home vpn, well... you wont notice it.