It most certainly uses GDI for Verdana. Firefox tried to disable that by overwriting the previous default setting for gfx.font_rendering.cleartype_params.force_gdi_classic_for_families and gfx.font_rendering.cleartype_params.force_gdi_classic_max_size, but restoring them fixed that.

Also this is not important. What's important is that DirectWrite does not render this font correctly, if you compare it with LibreOffice or Word.