I think it feels flat bc you dont rlly have a foreground(blue), just a middle ground(red) and background(yellow) I think if you pushed the door back, showed more of the path towards it, and added some darker bushes in the front it'd feel more 3dimensional. Overall your brushwork and colors are very very lovely, the palete u chose is very visually appealing, I think you could push it further by having more contrast in the values | Artwod Feedback