Sorry, I should have explained myself better. By "data" I mean the lighting (type, spectrum, intensity, duration which you have given), tank size, any plant additives, GH, plant species and numbers (a photo of the tank would answer this issue), etc.
And for the future, always give us the test numbers as we may need to know them.
It is a 90 ltr tank I have an l. e. d light I'm not sure what it is tho. It's fairly new tho. My pH is 7.6 nitrite and nitrate 0 and ammonium 0. I put a 2ml squart of tropica premium nutrition every other day and a 2ml c02 every day. Lights on from 2pm until 1030pm.
The plant in the photo is an Anubias? This is a low light slow growing species and mine did much the same thing. Floating plants may help.
On the CO2, I assume this is one of the so-called liquid carbon supplements? Seachem's Excel and API's CO2 Booster are two I know of, and they are both glutaraldehyde and water. Glutaraldehyde is a dangerous toxic disinfectant that can kill some plants at recommended doses, but if overdosed has the ability to kill plants, fish and bacteria. This is not a safe additive.
Not meaning to jump in on seangee, but as I am here...duration and intensity are two different aspects of light. Changing duration does not affect any issue (too much or too little) in the intensity. So here, I would lessen the light, and floating plants are an easy way to do this and keep the existing light.
Light intensity drives photosynthesis. So plants that need bright light, such as fast growing stem plants, will not be satisfied if the light is not intense enough just because it is on longer. And in reverse, low-light plants like Anubias will not do well under bright light even if it is on less.
This link shows how I have resolved the same problem in one of my tanks. I have a light side and a dark side, using a length of airline tubing to keep the floating plants on the dark side. The anubias in my case get very little light (intensity) and are thrivingBack to black