new to photoshop on pc, but it seems some colours are turning pixaly grey, especially when saturation is up. but it comes out fine when saved as jpeg.
It means you have View > Gamut Warning turned on. The gray is just an indicator that the color is out of gamut for the Proof Setup you have selected, so if you want to use Gamut Warning make sure the Proof Setup accurately represents your intended output.
thanks conrad, think I must have switched it on when using hotkeys to 'transform again'.