So after this afternoon's update did your text on your lock screen (not including your clock text) change colors? Well good news everyone with a brief talk to support through Samsung Members the answer is so stupidly simple. You wont believe it!
So the update from today tried to reset your lock screen background to the default setting messing with only the text but not the actuall wallpaper. So to fix this glitch just switch your lock screen wallpaper to something else and back again. That will fix your gray text issue right away.