First of all, you’re doing what to thaw frozen French fries? You could thaw frozen fries (called slacking) defined by the FDA food code as “The process of moderating the temperature of a food (held at room temp - not in water) to gradually increase from a temperature of -23 C (-10 F) to -4 C (25 F) in preparation for deep-fat frying or to facilitate even heat penetration during the cooking of previously block-frozen food…” though this is not recommended from our point of view – as even partially thawed frozen fries tend to absorb more oil and become limp.

As for the water discoloration described, this is most likely residue from the light seasoning or other coatings, which some frozen manufacturers apply for final fry caramelization (color) or flavor enhancement.