I think those are clear plastic spiral pieces that they place between tiles when packaging them. They act like tiny spacers between tiles in a box. They usually come off quite easily.

Have you touched them or tried to remove them? Used a blade scraper to try to remove them?

Acetone and a razor blade.

It's very hard. I tried the blade scraper. What else can I use ?

Is it on the surface or feels like it was baked into the tile finish?

Get a wet towel and let it sit on one of the "stains" to see if it softens up.

You could have a bad batch of tiles?

What did the tile installer say?

Heat one up with a hair dryer and pr poor some boiling water on one.

Thanks Everybody. I kept it soaked in Vinegar and water 50/50 solution for 10 mins. It worked .. 🙏🙏🙏

It's wax. Used for packaging. Very common. Warm water and a wallpaper scraper. It often comes off as one piece. Don't grout before removing. It will end up in joints causing problems.