What will happen if the car's carbon canister is not changed? Will it increase fuel consumption?

It has no effect on driving and has an impact on emissions.

Carbon canister is actually a part of gasoline evaporation control system, in which carbon canister is the most important key device, and the main function of collecting and storing gasoline vapor is accomplished by it. The carbon canister installed on the vehicle is actually an assembly. Its shell is generally made of plastic and filled with activated carbon particles that can absorb steam. The top is also equipped with a clean control valve to control the amount of gasoline vapor and air entering the air manifold and a filter screen to purify gasoline vapor.