The tile gap is dirty and black, How to DIY tile joint filler?
Fastobond Epoxy Grout for Tiles - 1 Kg - Black Color Epoxy Tile Grout_Fastobond | 3 Components only | Premixed Filler for Uniform Finish : Amazon.in: Industrial & Scientific
WHY BLACK GROUT TURNS ORANGE – AND HOW TO REMEDY IT | LTP_UK_Technical