I heard that fillers spread over time. Is that true?

I'm thinking about getting nose fillers or chin fillers.
I've heard so many people around me say that fillers spread out later.
I keep hesitating because I'm afraid I might regret doing it.

Looking at the photos, the effect is definitely good, but
The shape changes over time, or
It’s also scary because there have been cases where it went so far as to have to be melted down.

I wonder if the filler is really spreading.
Or I'm curious if it's a difference in the procedure or the product.

To do it safely
What should I check first?