For percentage closer filtering to be usable I needed to make two fixes at ShadowPercentageCloserFiltering.usf. I did forget to mention this.
Old:
// Wheather to enable the sharpening filter after PCF for sharper edges than the shadow map resolution.
#define PCSS_ENABLE_POST_PCF_SHARPENING 1
// Blocker search samples
#define PCSS_SEARCH_BITS 4
New:
// Wheather to enable the sharpening filter after PCF for sharper edges than the shadow map resolution.
#define PCSS_ENABLE_POST_PCF_SHARPENING 0
// Blocker search samples
#define PCSS_SEARCH_BITS 5
These mostly fixes noise and instability.