I don’t think, there is anyway to send multiple tracks via single transport.(if there is, please let me know),
If you want to send multiple tracks(typically audio and video), you need to need to produce both tracks one at a time using that single transport.
something like this:
const videoTrack = stream.getVideoTracks()[0];
const audioTrack = stream.getAudioTracks()[0];
const params = { track };
const params2 = { audioTrack };
this.producer = await transport.produce(params);
this.producer = await transport.produce(params2);