that’s an IceTech (Freeza ?) rotor with finned pads - typically a good combo to dissipate heat

agree with above post - contamination (grease, oil, etc) could have contributed to this

were the pads bedded in properly before heavy use ?

correct pads used ? this caliper / rotor combo uses ‘narrow track’ pads - as opposed to ‘wide track’ pads ... ( glancing at the picture I’m unable to determine if the pad is contacting the area beyond the brake track )

when you remove the pads - also check the calipers for oil, fluid leaking, etc - especially the area around the pistons ... clean this area with iso alcohol or similar ... might need to use a Q tip or similar