Can you file a labor case for holding EOSB without affecting your new job?

My son works in an education provider company in Dubai. He started the job on 22 November 2018. He is resigning on 06 June 2022.

The company told him that they need 3 months notice period. So he completed it. Now even though the company is enormously profitable, they are not ready to pay his gratuity.

His take-home salary is 4250 but his basic salary is shown as AED 500 (which is notoriously low). As per my calculation, he is eligible to get AED 1300 at least, but the company says they will not pay and he has to sign a no-dues certificate.

They said if he did not sign, they are telling him they will not hand over his degree certificate (again holding illegally without any proof) and the last month's salary.

My son worked so hard for them and he really deserves that settlement.

What will he do in this situation?

If we file a complaint in the labor court, does this become an issue for his new job joining?