Oh yeah something is definetely off with the plant, the fact that is taking the nutes from the lower leaves doesnt mean is okay (sometimes it is). I have autos in small pots, I dont give a lot of nitrogen, I lose a few leaves during flower from the bottom thats fine but this plant has something else. My SCROGs also tend to lose the leaves that I dont remove from below, also natural process but thats more explainable because the upper canopy blocks most of the light.
1st: Its not only happening in the bottom leaves
2nd: the fact that the stems are so tiny and its gonna be a single cola is unusual, could be a strange phenotype but that doesnt explain why some leaves that are not on the bottom are affected by something.
3rd: Dont put 2 plants in the same pot, its gonna be a mess with the roots and theyre gonna compete for nutrients. Specially in such a small container.
Yes, Ive had plants that didnt lose a single leaf, having even the cotyledons green from start to finish even tho is much easier when its a plant without training, specially non toped. Once you top the plant you will most likely get yellow leaves falling off in the future.