Issue with sending comments to Sanity studio from deployed version

export default async function comment(req, res) {
    const { name, text, email, _id } = JSON.parse(req.body)
    client.config({
        token: process.env.SANITY_API_TOKEN_COMMENT
    }).create({
        _type: 'comment',
        name,
        comment: text,
        email,
        post: { 
            _type:'reference',
            _ref: _id
        }
    })
    res.status(200)
}

const onSubmit = async (data) => {
      setIsSubmitting(true);
      try {
        await fetch("/api/comment", {
          method: "POST",
          body: JSON.stringify({ ...data, _id }),
        });
        setIsSubmitting(false);
        setHasSubmitted(true);
        setTimeout(()=>{
          setHasSubmitted(false)
        },3000)

        if(getValues('storeData')){
          window.localStorage.setItem('name',getValues('name'))
          window.localStorage.setItem('email',getValues('email'))
        }

      
    } catch (err) {
      console.log(err);
    }