If you're really using DejaVu Sans, that's a proportional font, so the difference to a "mono" font will be pretty big, especially for the usually narrow letters (i, j, l...) which have to be "padded" in mono fonts to avoid looking unbalanced (and, for coding, to make them easier to distinguish). Of course, if the other letters are as geometrically clean as in this font, the "i" will look a bit out of place. But actually in DejaVu Sans _Mono_ (https://www.fontsquirrel.com/fonts/dejavu-sans-mono), the "i" looks pretty similar.