Plain water won't get rid of oils and dirt. You need a detergent solution. Not detergent straight on the counter, a mixed detergent solution with water, and a microfiber. If that won't do it, then something else is going on. I'd bet something else, since it's MSI. Oxidation changes are not likely covered by warranty. Never use MSI. Low quality.

There is an enhancer out by Tenax specifically for quartz. You might try that after using the Dawn and a microfiber to rub that vigorously.

Thank you for the suggestions. I failed to note that we did try Dawn and water a couple of times, but no luck. MSI holds it self out as high quality. We purchased the premium Q series which was super expensive.

Also, what quartz company would you recommend should we decide to replace this?

Look for a granite, instead of quartz.

But it would break my heart to throw away a practically new countertop. The haze doesn't show in the photos (too much reflection). I hope you can find a way to restore your counters, or learn to live with the "patina" (though quartz certainly shouldn't have patina).

MB 20 on a white pad on a variable speed polisher will shine that right up.