Daily watering is likely far too often ... I'm not seeing quick useful links to peperone (as you can imagine, I'm getting a lot about pepperoni and pepperoncinis).

But if this is a C. annuum cultivar, these are adapted to arid climates. Let the plants tell you when they need water (droopy leaves); they spring back remarkably quickly, like in under an hour. It sounds like you're drowning them and ending up with other issues as a result.

I think you can use Diamacious earth on the top of the soil to kill the gnat/flies and future eggs. It’s completely safe to use just don’t inhale it a ton because it does have a small bit of silica in it.

It’s used as a dietary supplement as well so it’s food safe for animals and humans. It just isn’t for insects because it dehydrates their exoskeleton. It’ll turn kinda brown as you water on the top of it so just know that’s normal. It’s also very inexpensive.

Fungus gnats are extra annoying but something you can do in addition to watering a little less is to have some clean sand as a mulch over your potting mix paired with bottom watering your plants. I check my pots by feel on the bottom regularly to help inform when I water. For our inside plants and seeds I'm starting, I have a tray with ridges into which I can place the pots and some water. Seedling trays are widely available and a local greenhouse or nursery may have some headed for recycling rather than having to buy new plastic. If that same place does claim and mulches in bulk they may have sand that's suitable for short money since you only need a little bit.

By watering from the bottom, your potting mix will wick the water upwards through capillary action but the water will have difficulty moving into the sand because of the difference in texture and porosity and this will deprive the fungus gnats of the habitat they need to reproduce and continue to annoy you.

Water when the soil is dry, but before the plant gets droopy. The flies are probably around because it's too damp and growing mold.

insecticidal soap ­– fill a spray bottle with water, add a couple drops of liquid soap (Dr. Bronners or J&J Baby Shampoo)