onremovetrack -> onconnectionstatechange

[ugnich]

You need to replace deprecated onremovetrack with onconnectionstatechange:

Example:

connections[sid].onconnectionstatechange = function (event) {
        const connectionStatus = event.currentTarget.connectionState;
        if (["disconnected", "failed", "closed"].includes(connectionStatus)) {
            // user has left the building
        }
    };