I'm curious about the side effects of under-eye fillers..!

I have virtually no under-eye bags, so I'm considering getting under-eye fillers, but I'm hesitant because I've seen quite a few posts about side effects. At first, I took it lightly, but seeing posts about unevenness or a spread-out appearance is really bothering me. Still, I've heard that if it's injected correctly, it looks natural, so I feel like it might be okay as long as I avoid the side effects. If anyone has actually had this done, I'm curious to know if you've experienced any side effects!