I'd love to know if there's a way to fix the leaves!
There are so many reasons this could be happening! First, plants can get too much water or not enough water. Next, humidity levels can affect them too. Thirdly, plants don't like it when it's too hot or too cold. Fourthly, pests or fungi can get in there and make things tricky. And fifthly, plants don't always get all the nutrients they need.
I'm 100% sure it's because you're not using a pot with good drainage, right?! And the humidity is also wrong. That's why it's angry, LOL.
I suggest you water this plant at least once a week and give it indirect sunlight, which also affects why your leaves have brown spots!
It could also be due to pests like spider mites and fungus gnats, but don't worry, so many fertilizers are sold to keep plants healthy.