Jack is running with the dbus interface disabled.
Rationale: I don't want any apps to control Jack, and dbus
is not needed to become a Jack client.

A  Jack client named Pipewire with capture and playback ports shows in the graph window of QJackCtl.

And jack_lsp is reporting:

PipeWire:playback_FL
PipeWire:playback_FR
PipeWire:playback_0
PipeWire:capture_FL
PipeWire:capture_FR
PipeWire:capture_0

Output of the pw-dump command have many related config variables (or states); maybe you can use this information to craft a config that would not require jackdbus, so I suggest to enable jackdbus in order to better investigate.

Looking at the source, jackdbus is used to manage a pipewire sink/source:

https://gitlab.freedesktop.org/pipewire/pipewire/-/blob/master/src/modules/module-jackdbus-detect.c

And also to inform the jack-tunnel module with parameters:

https://gitlab.freedesktop.org/pipewire/pipewire/-/blob/master/src/modules/module-jack-tunnel.c

It looks like the parameters can also be provided by the pipewire config.

Marc