Underscore and `w` with some letters make `w` char smaller.

[blariise]

When typing _wf _wi _wj _wl _wt _wv, w char become really small.
Terminal: kitty
Font: font_family family='Monaspace Neon Var' wght=600 wdth=100 slnt=0 font_size 10

[madjxatw]

Besides underscore, this same with dot ..

[heathercran]

This is a bug in kitty where any characters that take up more than a full glyph width are resized (#222) or clipped (#303) to fit within the space of one glyph. This causes errors with our texture healing feature and some ligatures. You can disable texture healing (calt in OpenType features) to avoid this particular problem.