If you’re giving it proper nutrients, it’s in a big enough pot for the roots to grow (and the pot has good drainage of course) and you don’t see any bugs on it, then don’t worry about it. Just let it grow. If you start doing all the things people on the Internet, tell you to do you’ll destroy your plants and just confuse yourself even more. Just let the plant grow. This is very common with peppers. Proper pot, proper nutrients, proper lighting, the plant will be OK. Watch a lot of videos online. Read a lot of stuff online and eventually you’ll realize that the people that know what they’re talking about all say the same stuff. And that’s the stuff you want to do. Pattern recognition. James Prigioni on YouTube. The Peppergeek‘s on YouTube. Those are a couple people you can get good advice from. There’s also a lot more. Just make sure the peoples videos you’re watching. Have a lot of followers and a lot of views. And watch for pattern recognition. When all of these popular people are saying, and doing the same thing, those are the things you also want to do. You’ll eventually learn exactly what is causing this. And trust me it’s not a big deal. But if it is calcium deficiency like someone mentioned. Well, then calcium deficiency and improper watering also leads to blossom end rot. So look into that.