他の（全ての？）システムのユーザーが関与している？

[Canapin (Coin-coin le Canapin)]

It was discussed here as well:

Which system user account(s) should Discourse spawned processes run as?

It’s a quirk of how Docker works. The discourse user inside the container has UID 1000, so if you look at the process list outside the container it will show whatever user is UID 1000. In my case, it would show them as claudia as that’s the username all my servers use for UID 1000.