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I think you need to apply your shadows consistently. Is this a self contained work or for use in a project? Because i can see that that plants with shadows like that will likely have tiling issues unless the shadow is applied as a transparency on top of the tiles directly below. There's a reason most assets are self contained.
Try to keep your light source and detail consistent. Whilst also maintaining readability. Your plants are way more detailed then anything else which creates a visual clash. Try to keep the style consistent. The major issue i have is i'm not 100% sure what is going on in regards to the elevation. You have a gate, with high walls, but the top of the wall seems to have a walkway which continues back? Where does the gate lead? I can't tell the elevation of anything.
Also all your plants appear to be floating.