Quartz is tough, but you still need to take care of it. Usually, it's not damage that makes it look dull, but buildup on the surface.
Things like soap, grease, cooking oils, and hard water can leave a thin layer behind. This layer stops light from reflecting properly, making the countertop look dull. Some cleaners can also cause problems because they leave residue that builds up over time.
Another issue is cleaning too aggressively. Scrubbing with rough pads or powders can wear down the surface and reduce its shine.