My vector illustration was rejected, please help me to understand what's wrong

Hello everybody!
Yesterday I tried to upload an illustration, which was rejected after several hours. The reason is " it isn’t at the quality standard required to move forward".
I think my illustration isn’t good enough visually, so I decided to ask more experienced artists what is wrong on it and how I can make it better.

Here is the illustration. Thank you very much!

hi, as for me, I tend to rather like it , but, indeed, the global illustration is rather dark and lacking finition so to speak. Look at the window for instance, this is look like the light is being restrained inside, when necessarily this is going out to a bit … some shapes look also a bit too naive or even appear as not being perfectly executed indeed. The clouds , the big bushes are looking a bit randomly executed if u ask me … shadows are usually a bit too massive in my view and should be refined and turned more realistic

Thank you for the feedback!
I tried to repaint it a bit, taking your advices into account.
Now it looks this way

hi well I am sorry but I think that most of the things that I evoked were not really dealt with. u changed colors, I am not sure that this was such a good idea , since the global lighting looks somehow less realistic , if u ask me … I tend to believe that rather than chasing the global tone of the whole back, u should have kept it as before and emphasized the difference between lit parts and dark ones. Shapes still need to be smoothened , as well, most of them would be better if more rounded , especially as the shadowing inside most of the trees looks not realistic enough globally and tend to make shapes look like having “straight angles”. The lit windows also still keep on having no impact with the direct surrounding, which is far from realistic as I mentioned earlier on. For shadows I would recommend that u use the styles and shadow rather than than drawing some vector shapes , they would thus turn more realistic …