discord-player-play-dl/docs/youtube/cookies.md

Using Cookies to avoid 429

const { Player } = require("discord-player");

const player = new Player(client, {
    ytdlDownloadOptions: {
        requestOptions: {
            headers: {
                cookie: "YOUR_YOUTUBE_COOKIE"
            }
        }
    }
});

Keep in mind that using cookies after getting 429 does not fix the problem. You should use cookies before getting 429 which helps to reduce Error: Status Code 429