Although the granting of legal aid protects you from various costs incurred, it does not protect you from having to pay the costs of the opposing lawyer, for example, if you lose the case in the second instance, i.e. the regional labor court.
The court is also entitled to review your financial situation on an ongoing basis for up to four years after the end of the proceedings. If your financial situation improves, this may mean that you either have to pay installments on the legal costs incurred or pay higher installments than before.