I was just talking from experience at first. But for example searching I find various articles similar to this one

Increased abdominal pressure can lead to stiffness in the spine and added stress on the back. Tight belts can exacerbate this pressure, resulting in nerve compression, particularly affecting the femoral cutaneous nerve. This compression can cause not only back pain but also abdominal pain and discomfort, affecting digestive health. Evidence suggests that consistently wearing a tight belt can significantly heighten the risk of chronic back pain by disrupting spinal stability and altering abdominal muscle function. Visible signs, such as red marks on the skin after removing a belt, may indicate its tightness and potential for harm. https://wisehealthtips.com/can-lower-back-discomfort-be-caused-by-belts.html

Or this

Lower back and spinal pain Research has linked increased pressure in the abdomen with stiffness in the spine and extra stress on your back. So that extra ergonomic help you had from the office chair isn’t doing much if your belt still sits extra tight on your waist. The back pain is a terrible result of nerve compression which takes place when pressure is applied. https://www.askdrmanny.com/could-your-belt-lead-to-back-pain