The request to the SpeechKIT API is not working (401) - where is the error?

Question

JavaScript

Good afternoon, a request to Yandex.Api through the Browser returns an authorization error 401 :

although the similar code for NodeJS works.
I can't figure out what salt is.
Yandex documentation: description of the API method
My Code:

let api_key = '**********mySecretCode**********************';
    let params = new URLSearchParams();
const text = 'Привет!';
    params.append('text', text);
    params.append('voice', 'jane');
    params.append('emotion', 'good');
    params.append('lang', 'ru-RU');
    params.append('speed', '1.0');
    params.append('format', 'oggopus');
//================ кнопочка запроса ===================================
const fetchButton = document.getElementById("fetchButton");

fetchButton.onclick = ()=> {
    fetch('https://tts.api.cloud.yandex.net/speech/v1/tts:synthesize', {
        method: 'POST',
        body: params,
        mode: "no-cors",            //иначе ругается
        headers: {
            //'Content-Type': 'application/x-www-form-urlencoded',
            'Authorization': 'Api-Key ' + api_key,
        },
    })
        .then(res => {
        console.log(`responce is ${res}`);
        // return res.json();
        //const dest = fs.createWriteStream('./octocat2.ogg');
        //res.body.pipe(dest);
    })
        .catch(err => console.error(`!!! + ${err} + !!!!!!!!`));
}

Answer 1

It's hard to answer, as I understand it, you log in using a service account, maybe you forgot to assign a role? https://cloud.yandex.ru/docs/iam/operations/sa/ass... of
course, I could not go further, I did not create a paid account.