I’d say don’t fret, only a 20% dilution... and it wasn’t your car.
I once returned a rental van filthy dirty and gladly paid the cleaning charge.
All the mud covered the scratches I left on one side backing it into an underground garage parking spot.
Vehicle had a whopping 47 miles on it.
Oops.
Guy at the rental place signed off with it dirty.
Instantly the damage was pre-existing.