A collective bargaining agreement negotiated by a school district and an exclusive representative of the employees in accordance with the act of July 23, 1970 (P.L. 563, No. 195),¹ known as the Public Employe Relations Act, after the effective date of this section may not provide for a rating system other than as provided for under this subarticle. A provision in an agreement or contract in effect on the effective date of this section that provides for a rating system in conflict with this subarticle shall be discontinued in a new or renewed agreement or contract or during the period of status quo following an expired contract.