I had a blister on my foot and it left a mark its not red or white its just kinda of a brown colour. is this a scar. the blister was due to friction?

I understand you would like medical advice, but this forum is not designed for personal advice. In addition, as you realize it would need to be seen. You should see a doctor in person. Best of health and peace

Because people often have 'Foot wears' of one sort or the other, the tendency is that the foot is usually warm, moist and not well ventilated allowing for Fungal growth and some debris to settle there. Foot hygiene is necessary but One should see a Podiatrist first for evaluation.

It is likely that the friction that cause the blister also caused some bleeding into the tissue and you seeing the residue of that reflected as brown pigment. It will resolve but may take months or even longer for it to resolve fully. It is not a cause for concern, unless you see a discharge from it or it becomes painful. Wish you good health!