Nothing has changed with respect to color-controls recently.
At least not that I'm aware of. I've not encountered any problems re color-controls since as long as I can remember.
Cannot the "environment" of your PC have changed?
Otherwise e.g. try a different videorendering.
What codec/filter are you using for playback? (With a video file loaded: (rightclick >) "Options" > "Filters" > Advanced)