Comment by Kamil Maciorowski on Is there a way to keep track of all processes created by an application (specifically chromium) and kill them all when it is closed on CachyOS?

Here: "If you want to confine an arbitrary process so that it and its children would be easy to stop – either make it a systemd service or use systemd-run and either way you'll get a dedicated cgroup whose contents can reliably be found later".