TwizzleStix
Pudendum Inspector aka FORZDA 1
After listening to your clip again closer in a quiet area, a loose brake caliper could indeed make the rattling sound. Not necessarily a “loose” pin though. I haven’t had the brakes apart on mine yet, but many/most oem brakes have a rubber isolator sleeve or lube dust boots that the pin goes through to prevent such rattles. Anyway, you’re likely fixed.