the presence of which was causing Thunderbird to display ugly text.
-font-adobe-100dpi
-font-adobe-75dpi
font-adobe-source-code-pro-2.038R~ro+1.058R~it+1.018R~VAR_1
font-adobe-source-code-pro-2.038R~ro+1.058R~it+1.018R~VAR_1
-font-adobe-utopia-100dpi
-font-adobe-utopia-75dpi
-font-adobe-utopia-type1
fontconfig-dbg
font-iosevka
font-misc-misc
fontconfig-dbg
font-iosevka
font-misc-misc
xorg-input-drivers
xorg-minimal
xorg-video-drivers
xorg-input-drivers
xorg-minimal
xorg-video-drivers