Many, probably most, store-bought stains are made with both dye and pigment. If wood stained with these stains is exposed to sunlight or fluorescent light for a while, the dye color will fade away, but the pigment color will remain. The effect is that the stained wood changes color.
In the accompanying picture the red dye in this “cherry” stain has faded on the top half (I covered the bottom half) after only a few days in direct sunlight, leaving the color significantly different. It’s definitely no longer cherry color.
The fading occurs much more rapidly in direct sunlight than indoors with a window providing a partial barrier to UV light. Nevertheless, you need to be aware of the problem when choosing a stain, depending on where the object will be placed.
To my knowledge manufacturers never tell us if there is dye in the stain, so we have to determine this ourselves. The easy way is to open the can after it has sat on a shelf for a week or two to allow the pigment to settle, then insert a light-colored wood stirring stick an inch or so into the stain. If it colors the stirring stick, there is dye in the stain because dye dissolves; it doesn’t settle.
If you insert the stirring stick to the bottom of the can, and the pigment has fully settled, you should be able to bring up a little pigment. Very few stains contain no pigment, but some do.