Constrain proportions [Make the behaviour consistent throughout Photoshop]
On raster images, the old behavior was hold down shift to constrain proportions. As of CC19 constraining proportions is now the default behavior while shift becomes the modifier. I'm all for efficiency and I don't have a problem learning a new behavior (even if it has been engrained in my head for the last 20 years) but for the love of god, can you at least make it consistent across the application? Live shapes in photoshop (ellipses, rectangles, polygons) still require shift to be held down in order to constrain proportions. Trying to use both shapes and raster images in a file will drive you absolutely mad.