A single little black fly (?) is stressing me out

There’s been a singular tiny black fly (or flying insect) that’s been chilling in my plants’ soil. I pretty much only notice it because it flies away when I water the soil of a plant.

I’m pretty new to this and don’t know pests well, so I’m paranoid it’s something laying eggs 😅 I’ve applied diluted neem oil (5ml/liter) to my plants’ soil, just in case.

Is this something I should actually worry about?