That's because Kepler-186f orbits a red star, and we're just speculating that perhaps the plants there, if there is vegetation that does photosynthesis, it has different pigments and looks red.
Esto se debe a Kepler-186F orbita alrededor de una estrella roja, y solo especulamos que tal vez haya plantas allí, si hay vegetación que hace fotosíntesis, tiene diferentes pigmentos y se ve roja.