Why does the Xiaomi Buds 5 leak sound when worn?

The earbuds are designed with a semi in-ear structure to provide a comfortable and relatively loose fit. The semi in-ear structure differs from fully sealed in-ear designs by not creating a tight seal within the ear canal. This openness can result in some sound escaping from the earbuds, which is a normal characteristic of this type of earbud design. This design allows you to remain aware of ambient sounds while enjoying music or calls. It strikes a balance between comfort and situational awareness, which inevitably leads to some sound leakage.