Need some help indentifying this...

Ok so, I have acouple questions. First off, check out the picture and tell me what ya think it is... I doubt it is heat stress because it is only happening to the lower fan leafs. Second question, I have some gnats in the room. are they something to worry about, if so, How do I kill them and their larva(which i can not see any larva, probably because they are so damn small)?

All suggestions and comments are welcome.

get a fan and get kill the flys they live on the underside of the leaf and in the soil find a way to cover the soil (paper plate)

yaaa I put the fan back on em, I took it off for a bit but things are better now haha, leaves are still coming up weird colours tho...