A peak going “off the top” of the histogram just means a very large number of pixels share that brightness level. The histogram’s vertical axis shows how many pixels are at each tone; left is darker tones, right is brighter tones.

So this is not automatically bad. It only becomes a problem if that pile-up is slammed against the far left or far right edge, which can indicate clipped shadows or blown highlights. If the tall peak is somewhere in the middle, it usually just means the image is dominated by a narrow range of tones.

In your example, the answers suggest the image is probably fine. If anything, it may indicate unused brighter tones, meaning you might be able to expose a little more to use more of the available tonal range—but only if doing so doesn’t push highlights into clipping.

To avoid this when it is a problem, watch whether the histogram is bunching up at the extreme ends, and adjust exposure accordingly. A logarithmic histogram view can also make differences in darker tones easier to see.