Yes it can. Things like sulpher, chlorine, and other trace elements can react with chemicals in the grout itself. These can do anything from lightening the color (chlorine) to darkening it (sulpher). They can cause iit to have a greenish tint (copper) to a blueish tint (cobalt).
Here in lyes the reason that tile layers will stop, and start all grouting at a doorway, or other place that has a transition and will not show small diffrences in the grout color.
Unfortunatly there is no cure for this problem except to re grout the whole area.
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Best regards; The Home Smithy