Looks like Chrome 61 enabled following the colour profile for the monitor.
https://productforums.google.com/for...e=forum/chrome
Unfortunately Windows doesn't have a colour profile for my monitor. I'll have to see if I can find one on Dell's site.
There's a flag to disable it: chrome://flags/#enable-color-correct-rendering
Now it's back to normal, man I thought I was going crazy there for a little bit. "Am I having a stroke, everything looks so wrong"