I did it 5 years ago at a famous lip filler house and it didn't melt.
No matter how expensive and famous it was and the director took good care of it, it was done in a factory way to some extent.
At the time, I didn't need a lip corner filler, but I put it in as I wanted.
I just don't use fillers. I'm too afraid of the side effects.
I haven't had any side effects, but I will never do it in the future.