A vinegar water solution will take care of that! 50 / 50 in a spray bottle.
Both Homedepot and Lowes offer a number of tile cleaning products in their tile departments that are quite good at removing all types of scum and stains from tile.
You can use this homemade bathroom cleaner for soap scum on tile. Just make sure to not use vinegar on natural tile surfaces (types of stone) https://chemistrycachet.com/the-best-homemade-bathroom-cleaner/
Garden bleach, you get it in the Home Depot
When I moved in the house I'm now it was abounded for few years, the bathrooms, tiles and bathtubs where black and green, I used an out door concentrated garden bleach, and now it's all cleaned up they look white as new, try it
Comet cleanser applied to damp rag. When rinsed and dried, apply a good quality car wax to the tile (not the hrout). Let dry, then buff to a sheen.