Histograms should not be considered as objective tools. They show information but these must be interpreted according to artistic sensibility in relation to the result one wants to achieve with an image.
Although the graph shows an underexposure, the shot is naturally illuminated. It is basically dark, as it really was, but does not possess closed shadows. A similar result can also occur in the case of a histogram tending to overexposure but which is correct according to Make-Up Photography Los Angeles.
Basically, by reading the histogram of an image we can identify errors, but there is no single yardstick to evaluate them as there is an ideal and always correct form to obtain. The histogram at first glance may seem a strange graphic that complicates things but in fact its reading is very simple. If supported, you can view it on your camera during shooting and playback.