I have exactly this setup at my house.
Garage supplied from the house CU via 16mm² SWA and a 50A type C circuit breaker
Shed supplied from garage CU via 6.0mm² SWA and a 32A type B circuit breaker
Shed has 4 final circuits.
1: B20 RCBO socket radial
2: B6 tubular heater
3: B6 inside light
4: B6 outside PIR light
What part of this is bad design?