I also encountered this, there’s a few new default post processing options which affect the global colour grading of 4.19
You’ll need to create an unbound post process volume to see the difference in editor, the options are:
Catgeory: Colour Grading > Misc
Blue Correction
Expand Gamut
If you set them to 0.0 it looks about the same as 4.18.
Hope this helps.