I had this head mesh with shape keys for customization. I had to get some "ideal lip shapes" and per my taste I first gravitated toward lips that had an indent in the aforementioned bump. Sorta like if a woman gets too much lip filler it kinda looks like 2 pillows squished together. But when I looked up references of eastern character designs sure enough to all had this beaky bump.
So I came to a point where I had to redo the head mesh and I just redid all the lips morphs last night. I really "winged it" didnt use references and didn't have a plan. Just need some shapekeys for my game scripts to grab onto.