I'm having the same issue. It's so sad that almost a month before your post, no one, not even a moderator responded with a solution or something like "We're aware of this, our team is working on a fix".
I had this problem since 3 months ago, then I downgraded to 18.5.1, and it fixed the issue. Some weeks ago I updated to 18.12.1, and this issue came back. I hate the fact that I'm forced to watch videos in fullscreen to minimize this color delay effect.