If you are using vercel as your website distribution tool, choose the option that is not the www.yourdomain.com redirect method, because this is also related to

https://support.google.com/adsense/troubleshooter/9556696?sjid=4393915934782411537-AP#ts=9805619%2C9816534%2C9817103%2C9817628%2C9817199%2C9817631

To strengthen it, you can also set it in robots.txt so that /ads.txt is allowed to be accessed and indexed by Google crawl.

Here is the syntax in robots.ts

export default function robots() {
return {
    rules: [
        {
            userAgent: '*',
            allow: ['/', '/ads.txt'],
            disallow: ['/privacy-policy'],
        },
    ],
    sitemap: `${process.env.NEXT_PUBLIC_BASE_URL}/sitemap.xml`,
};

}