I followed your suggestions to clean bathroom wall tile grout. The last solution I used was creating a mixed paste of baking soda & water, which I applied to the grout lines. Then I sprayed with an equal mixture of vinegar & water. Once the bubbling finished, I wiped the bathroom wall tiles down with clean water. I now have discoloration on the tile at the grout lines. See photo. The porcelain tiles are light cream in colour, the grout is peach.
Is there anything you can recommend that I use to remove these new dark tile stains?