Could you help me to find why my leaves are in two colors? Dark and white green in the same leaf.

I'm with Ezzjaybruh here... just genetics....

That is a genetic thing and of no concern -- the drastic 2-tone of color. -- "Variegation" you can google image search to see this is exactly what you got here. you may or may not have hints of inteveinal chlorosis, the leaves are a little patchy, relative to each natural color displayed. Little tip burn in the overexposed picture. How it progresses, where it is on plant can help deduce what the cause is. More than one thing causes most symptoms seen, so you have to cross-reference other bits of information to figure it out. if the other plants don't show simila signs, excluding the variagation, then any changes should be small and slow. it takes weeks not days to see a full impact of any formula change. and if in soil, even longer transition between previous and new formulas.

Also. I can see light mag issue between vains on white bg

You need a boost in PK. Good luck