Steam Api trade offers

Question

This script was created as copy from actual request (DevTools in Chrome), all data is correct. All headers was tacken from devtools

headers = {
        "Accept": "application/json",
        "Accept-Encoding": "gzip, deflate, br",
        "Accept-Language": "en-US,en;q=0.9,uk-UA;q=0.8,uk;q=0.7,de;q=0.6,bg;q=0.5",
        "Cache-Control": "no-cache",
        "Connection": "keep-alive",
        "Content-Type": "multipart/form-data; boundary=----WebKitFormBoundarymL5xUCjVIjTJLrqB",
        "Cookie": "xxxxx",
        "Host": "steamcommunity.com",
        "Origin": "chrome-extension://mkjknmlmebnimmkonggecjlccealonel",
        "Pragma": "no-cache",
        "Referer": f"https://steamcommunity.com/tradeoffer/new/?partner={partner}&token={token}",
        "Sec-Ch-Ua": "\"Google Chrome\";v=\"119\", \"Chromium\";v=\"119\", \"Not?A_Brand\";v=\"24\"",
        "Sec-Ch-Ua-Mobile": "?0",
        "Sec-Ch-Ua-Platform": "\"Windows\"",
        "Sec-Fetch-Dest": "empty",
        "Sec-Fetch-Mode": "cors",
        "Sec-Fetch-Site": "none",
        "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36",
    }
    
All data seems to be good, but something isn`t working
(All variables are 100% correct)

data = {
        "sessionid": "xxx",
        "serverid": "1",
        "partner": f"{partner_id64}",
        "trade_offer_create_params": f'{{"trade_offer_access_token": "{token}"}}',
        "json_tradeoffer": {
            "newversion": True,
            "version": "2",
            "me": {
                "assets": [
                    {
                        "appid": "730",
                        "contextid": "2",
                        "amount": "1",
                        "assetid": f"{asset_id}",
                        "classid": "",
                        "instanceid": ""
                    }
                ],
                "currency": [],
                "ready": False
            },
            "them": {
                "assets": [],
                "currency": [],
                "ready": False
            }
        },
        "tradeoffermessage": f"OfferID: {offer_id}",
        "captcha": ''
    }
    response = requests.post(url, headers= headers, data=ujson.dumps(data))

Gives me a 401 error.
A 401 status code indicates that the request has not been authorized. In the context of Steam API requests, this might mean there's an issue with the authentication or session information. Tried to change the values of variables from str to int (didn`t work)