Is my RCD Breaker faulty?
RCD will trip on a ground fault. Sometimes an older refrigerator or garbage disposal will cause them to trip.
Since it appears to have a cycle it may be a defrost setting in the refrigerator causing the fault.
It is possible the breaker itself is faulty but I would expect a more random tripping if this was the case.
Are there any other appliances that have a “cycle” if not try changing the temp in the refrigerator, colder might make it trip more often warmer less often if it is the defrost cycle.