Why GMail with Google Sans is ugly on non HDPI screens

Please notice how 'z' is drawn - top edge is doubled comparing to Arial's 'z'. Also strike in Google's 't' is affected by the same unpleasant readability problem. Google Sans looks dirty while Arial is clear. Let's open Google Sans is TTFEdit from Source Forge. Written by me about 12 years ago in Java 5. Height of 'z' from Google is 500 units, while 'z' from Arial is designed on area with height 1024. Font renderer is optimized for fonts which created Internet and they for base use 1024. As a result modern 'z' is scaled strange way and looks ugly.