What's wrong with the leaf?

Have you been spraying the plant or wetting the leaves?? New growth is ok, don't worry too much, it is not a disease. Quite often, damage like this is from the leaves resting on the soil at night when the lights are out and the plant lowers its leaves. It is 100% NOT septoria, which is almost impossible to get, unless you dig up soil from an infected tobacco farm and spread it around your pots. Always wait for multiple answers when you post a question and never go with the first random answer.........