Hello partners

Got called in to look at this marble shower that was installed about four weeks ago. They used bright white epoxy grout from Laticrete. I’ve attached a picture of the shower tile. The material is from Best Tile and is called Dolomite Select polished marble 12”x24”.
It is a steam shower and has been used several times over the last month. Initially there was no staining around the grout lines according to the contractor. I believe the homeowner started noticing it after they started using the steam which was about two weeks after install.
It’s strange because the Jacuzzi surround which is not in the steam area has some darkening also in certain areas.
Most of the darkening inside the shower is down low. Also had some blue staining appearing but the contractor was able to remove most of it with the poultice.
Has anybody had this issue? This particular marble I know is very easily darkened. I installed some vanity tops  recently and had used 100% clear silicone to attach to the vanity top to cabinet. The darkening lasted for 2 to 3 weeks from the silicone. But eventually it went away.
Not sure if the epoxy grout is causing an issue or the steam is getting in the edges of the tile.
I would appreciate any thoughts on this.

Thank you,
Chris Santospago
Restoration by design stone

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