It is not clear that this gall midge produces a gall. Infection is detected by looking for necrotic lesions very low on the stem--basically just above the soil line. Neither paper cited below mentions any type of hyperplasia, but the severe damage to soybean crops may have led some slight galling to be overlooked.

Photo 1 does give an impression of a gradual swelling of the stem. However, the plant in the photo is probably being held upside down to make the midge larvae easier to see. McMechan et al. (2021), the source of both photos here, does not mention stem swelling nor does Gagne (2019).