Almost everything that goes wrong after a renovation shows up late, because it needed the finished room to appear. Most of the causes are the light or the new neighbours, not the paint. Find the mechanism first, then start with the cheapest change.
Pick whichever is closest. You do not need to know why — working that out is the point.
Try the cheapest, most reversible change first. Lighting before textiles, textiles before furniture, and repainting well down the list rather than at the top — because the light is the most common cause of a colour looking wrong and the least expensive thing to change, and because a fix you can undo in an evening is worth trying before one you cannot.
Each step costs more and is harder to undo than the one before it. That is why the troubleshooter always works from the top, and why repainting appears so far down.