This is just a warning. From what I see it comes because rtp module is loaded. You can see this by
Code
LibreELEC:~ # pactl list short modules |grep rtp
18 module-rtp-send source=librespot_sink.monitor destination_ip=127.0.0.1 port=6666 source_ip=127.0.0.1
And seems it is used/loaded by librespot: LibreELEC.tv/librespot-03_pulseaudio_sink.patch at master · LibreELEC/LibreELEC.tv · GitHub
You can unload it by
but maybe functionality will stop working.