Generally, for a person to acquire Slovak citizenship by birth, it was sufficient if one of their parents was a Slovak citizen at the time of your birth.
Therefore, it is presumed that you or subsequently your descendants, could have acquired citizenship by birth. It is probably sufficient to apply for a certificate of citizenship and there is no need to apply for citizenship through ancestry, as you could have acquired citizenship by birth. If the authorities discover during the process that your mother's citizenship was cut off before you were born, you are then eligible to apply for citizenship.