Please add this to wireplumber.service:

    [Unit]
    ConditionUser=!root

This is consistent with existing rules (though all should use "ConditionUser=!@system"):

    /lib/systemd/user/pipewire-pulse.service:ConditionUser=!root
    /lib/systemd/user/pipewire-pulse.socket:ConditionUser=!root
    /lib/systemd/user/pipewire.service:ConditionUser=!root
    /lib/systemd/user/pipewire.socket:ConditionUser=!root

Before:

    systemd[725]: pipewire.service - PipeWire Multimedia Service was skipped because of an unmet condition check (ConditionUser=!root).
    systemd[725]: wireplumber.service: Bound to unit pipewire.service, but unit isn't active.
    systemd[725]: Dependency failed for wireplumber.service - Multimedia Service Session Manager.
    systemd[725]: wireplumber.service: Job wireplumber.service/start failed with result 'dependency'.
    systemd[725]: pipewire-pulse.service - PipeWire PulseAudio was skipped because of an unmet condition check (ConditionUser=!root).

After:

    systemd[700]: pipewire-pulse.socket - PipeWire PulseAudio was skipped because of an unmet condition check (ConditionUser=!root).
    systemd[700]: pipewire.socket - PipeWire Multimedia System Socket was skipped because of an unmet condition check (ConditionUser=!root).
    systemd[700]: pipewire.service - PipeWire Multimedia Service was skipped because of an unmet condition check (ConditionUser=!root).
    systemd[700]: wireplumber.service - Multimedia Service Session Manager was skipped because of an unmet condition check (ConditionUser=!root).
    systemd[700]: pipewire-pulse.service - PipeWire PulseAudio was skipped because of an unmet condition check (ConditionUser=!root).

I think this also affects upstream, but I have not thoroughly looked through all upstream branches/bugs/pull-requests:

https://github.com/PipeWire/wireplumber/blob/master/src/systemd/user/wireplumber.service.in