What does the light bulb say, or is it LED
What brand tank is it?
[40L is ~23.5G just for those who aren't wanting to look up the gallons.]
It could be a looking at the fish light and not a growing plants light!
vallisneria in the back corner
Anubias - likely Nana variety with rocks
Marimo Moss ball
Cryptocoryne Parva the light green plant on the side by the tall dark rock
Crypt wendtii in front of the big rock maybe bronze variety
Amazon Sword behind big rock, Needs root capsules /tabs it is a heavy root feeder
the little green plants sticking up, I can't see if they are, maybe Staurogyne Repens if they are more like leaves.
or Dwarf Sagittaria if they are more like grass and flat leaves.
Dwarf Sag as it is often referred to, has a stem which is round and the flat leaves come off of it. The Dwarf Vallisneria has flat leaves look more like individual leaves coming up off of the rooted area.
Will grow longer with poorer light, due to stretching.