Grout color coming off

I moved into a 2 year old mobile home (renting), and the kitchen has black granite tiles on the counters with black grout.
The color from the grout comes off on my hands, clothes, or towels; I cleaned only with water and white vinegar, as I have asthma and am chemically sensitive. (It is not mold or dirt, it is the pigment of the grout.) There are also some areas where fine sand is coming off.
The manager said the grout needed sealing, he used TileLab grout sealer (Low VOC) as directed and applied 3 coats.
Now, 24 hours later, there is no change, the color still comes off easily.
I am concerned not only for ruining my clothes and linens, but food safety.
What now?

STOP using vinegar to clean the grout. Seal it again and again until it stops taking the sealer. Not sure Tile Lab brand is the best choice of sealers in this case.

Thanx, Bud Cline Tile, I misspoke, not that I use vinegar to try to stop the color from coming up, only meant to say that I have not used anything harsher as a cleaner. Mainly I have just used wet paper towels and there is ALOT of black coming up, like the whole towel is covered. Was not trying to clean the grout, just to wipe down the counters and found that the grout was coming off.

Would the only product that would work to seal be a toxic one? I can not tolerate those.

How many coats of sealer would it take? 3 were already applied.

Thanks.

Is it coming off rhe grout lines? Or was the grouting not preoperly cleaned and you're just wiping off residue on the tiles?

Sounds like someone didn't clean up after themselves very well.

I doubt it is residue. I have wiped it many, many times with a wet paper towel, in fact went thru a whole roll. I have been thru some major remodels before and have never seen anything like it, and know others who have black tile kitchens (popular in this area, why is beyond me) and they didn't have this kind of problem. It is only coming off the grout lines themselves. It is like someone wanted to make them darker and used a magic marker on the grout lines. Only it won't stop coming off.

This tile is not new, was supposedly put in when the home was first put on the lot, and there was another tenant here before me, is well over a year old.

Black grout is the worst color to work with. For some reason it has a soot like nature to it. It is very hard to clean thoroughly. I suspect you are just wiping off some residue.