Unilateral upper eyelid hallowing after Botox of glabella (Photo)

So this has happened both times I’ve had Botox. The first time, I thought it was injector error, so I went to another place (reputable practice, saw a PA with many years of experience) and it still happened again. So I’m wondering if it’s something unusual with my anatomy, and how to prevent it in the future? I would love any ideas on how to fix it if possible because the first time, it lasted 6 months. I had 20 units the first time and 16 this time. My forehead was not treated.