Message: Missing required parameter "content_type"

Extensions
4

Pulling from my sender:

Try

const payload = {
    exp: Number(Math.floor(Date.now() / 1000) + 60),
    channel_id: String(channelId),
    role: 'external',
    pubsub_perms: {
        send: [
           'broadcast'
        ]
    },
};

and maybe: (just omit the algo) then your code matches mine

let signedJwt = jwt.sign(payload, secret);