Visual albedo is the measure of the reflection of sunlight out of the total solar radiation received by an astronomical body, taking into account only the visible light. The visual albedo of the Earth is 0.37, and the Moon’s is 0.12.
The Moon appears dark if the Earth also appears in the same photograph. Flat Earthers use the fact to dismiss such photos as fake. In reality, the Moon’s brightness in a photo is just a matter of choosing the correct camera exposure. But if Earth is also present, increasing the exposure will make the Earth appear too bright.