see this link item 2
https://blog.securepaystubs.com/posts/social-security-tax-for-employers-a-complete-guide-to-complian...
have you approached the employer of this issue and what did they say. if anything?
your recourse would be to contact the iRS but you might also need a lawyer to recover any amounts illegally withheld.
you may be subject to federal income tax withholding. so are you sure this isn't what the employer is doing.
