Broken supports (or missing parts of supports) are usually caused by incorrect settings in PrusaSlicer – the supports are either too thin or the exposure time is set to too low value. In some cases, this can be also caused by a faulty UV LED panel or dirty FEP film.
Solution: Try printing one of the sample objects to see whether the issue remains. If the sample object was printed without trouble, reset your PrusaSlicer settings. If the sample object has the same sort of trouble, inspect the FEP film in the resin tank – it may be dirty. In very rare scenarios, a faulty UV LED panel can be the cause.