A histogram isn’t supposed to look a certain way. It should match the tones actually in the scene.

For a wine bottle product shot, a histogram with lots of dark tones and bright tones but few midtones is completely normal. You have a mostly dark subject, bright specular reflections, and often a white or very bright background. In a studio flash setup with little ambient light, that separation becomes even stronger: reflective areas jump toward the right side, while parts of the bottle that don’t reflect light toward the camera stay dark.

So the missing midtones usually aren’t a problem by themselves. If the photo looks right and you’re not clipping important highlights or shadows, the histogram is likely appropriate for the subject.

If you want more midtone information, you’d need to change the scene itself: add more medium-toned elements, reduce contrast, or alter lighting so more of the bottle records as medium brightness. But don’t try to force a “better” histogram if it makes the image worse.