After making several adjustment layers, the layer merge is performed. However, it is observed that the colour changed after layer merging. It is confirmed with the histogram. This phenomenon also happens in layer flatten. Any solution?
By any chance did this start after a driver upgrade?
If it does not, you are seeing normal behavior. The color change is due to
the layer effects being applied to the preview, the preview being an
approximation to the actual image.
And until you update it, it's a lot less accurate with many adjustment layers than it is with a flattened image.
click on "blending modes" in the "fx" at bottom of layer palette
tick the box "blend interior effects as group"
see if it gives better result