Replace the tile.
You may have micro scratched the surface, or if he sealed over the grout and tiles, you may have abraded off the sealer.

Prior to doing anything extreme, I'd recommend using a commercial grout haze remover on the tile.

Depending on how long the residue has been there, if less than 10 days use a standard grout haze remover, even one designed for clean up during the grouting process itself. If over 10 days you sometimes need to step up to something stronger, along the lines of a phosphoric acid cleaner.

Caveat, the stronger the product, the more damage you can do.

I recommend calling Aqua Mix tech support, 800-282-8786 and relating to them the products used.

After using the removers if you still have variations you could rent a buffer to try to even out the overall sheen of the floor, but it really depends on what is causing the areas of dullness. Residual haze or tile abrasion?

If it was sealed, the porcelain shouldn't have been sealed. No reason, it's not porous. Sealer over porcelain can cause problems instead of preventing them.

A question or comment though...the tiler should be responsible for cleaning up the original haze. Not you.

It is mentioned ""diluted vinegar/water mix to scrub it off""

What tool was used to scrub with?

Hand?
Washcloth?
Brillo pad?
Steel wool?
Scruffy pad?

Thanks folks. Floorguy, I used a regular nylon bristle brush. Any fix you know of?