Try Soft Scrub with bleach. Just make sure to shake and apply the Soft Scrub to a wet rag first and then softly rub the counter and rinse. Let us know if that works.

I agree with above - try cleaning it all again. I’ve been using Method cleaner on my white/gray quartz for years no problems.

I cleaned it all again with method to make the surface look even... but not sure only that part looks discolored even after that.

Also, I tried weima‘a quartz cleaner and still no luck

I just use a bit of Dawn dish soap.