Plus the filler is absorbed by the body, but at different rates. So in a few years it’s gonna be irregular and lumpy. Some people go to the extreme length of having glass microbeads mixed with the filler (this is illegal in the US) but those migrate around within the tissue. Once you start this shit, it’s just a constant Death Becomes Her maintenance operation to keep it from looking worse.

Or as they say in Ab Fab, “pretty soon you’re a just visitor in your own face.”