This occurs when you restore a configuration file from one operating system onto another.
The scrub directive, used for packet normalization, has undergone significant changes. pf configuration incompatible with pf program version
Furthermore, options like tcp.max-mss have seen syntax adjustments. An older configuration utilizing scrub directives with deprecated parameters (like no-df being handled differently or specific fragment reassembly options) will trigger a parser error, resulting in an incompatibility report. This occurs when you restore a configuration file
pfctl -F all