It would help to know the equipment in which the problematic gasket are and also few information such as in which process (treatment, chemicals, etc), are they brand new gasket , 6 months old when they broke, etc.
Is your system just aging? That’s a primary cause of elastomeric degradation. I know I see failures in batches due to age from time to time and that makes it seem like maybe something else is going on.
That’d be my guess if you haven’t really changed anything. If you switch from chlorine to another disinfectant, however, that could be the cause of your issue as well.