It would make no sense to ban an IP for only a single session. Shadowbanning can still be rare (for whatever value of rare) when an IP ban is persistent.

If you want to ban some IP, just serve 403 to that IP. Deleting all of the accounts of people who like to order toast and eggs in the morning at the same place is what makes no sense.

> Deleting all of the accounts of people who like to order toast and eggs in the morning at the same place is what makes no sense.

Shadowbans are reversible by users and can be appealed to the mods, assuming you notice it (which, by design, you're not supposed to.) This is supposed to ensure that only accounts which should be banned remained banned.

It's not perfect, but it does make sense - the only real options for banning are by IP and by account, so if you want to prevent a banned user from just making a new account, you have to ban the IP as well. Maybe someone was a troll and got that IP banned, maybe it appears on a blacklist (assuming HN checks that,) who knows? It's not random and arbitrary, though.

have you contacted the mods about this? It should be a fairly easy to verify and fix.