If a flashlight were pointed at the Sun from the deepest point of the Challenger Deep in the Mariana Trench, the photons emitted by the flashlight would travel through the water toward the surface. However, as the depth increases, the intensity of light decreases due to the absorption and scattering of photons by water molecules and suspended particles.
In the Mariana Trench, the water depth is approximately 36,000 feet (11,000 meters), and at such depths, very little sunlight can penetrate. As a result, the photons from the flashlight would not make a noticeable difference in the amount of light reaching the trench floor from the Sun.
The sunlight that does manage to reach the depths of the Mariana Trench is already significantly diminished and appears as a faint blue glow. This is because water absorbs and scatters light, with shorter wavelengths (such as blue and green) being absorbed more readily than longer wavelengths (such as red and yellow).
So, while the flashlight photons would contribute to the local illumination in the immediate vicinity, they would not significantly alter the overall lighting conditions in the deep trenches. The natural sunlight that manages to penetrate those depths is already greatly attenuated, resulting in a dim, bluish environment.