Created attachment 172423 [details]
Blurry bold font when using Cantarell

SUMMARY

When using Gnome, if you install QT applications which use bold font the bold font is rendered blurry.

STEPS TO REPRODUCE
1. Install Arch
2. Install Gnome including the default font Cantarell
3. Install KDE applications such as Kasts

OBSERVED RESULT
Bold text is rendered blurry

EXPECTED RESULT
Bold text should not be rendered blurry

SOFTWARE/OS VERSIONS

(not relevant, since running on Gnome)

ADDITIONAL INFORMATION

Hello,
On Arch + Gnome 46.4 (both Wayland / XOrg) bold text in QT apps is rendered blurry, unless you are using Noto Sans, Roboto or Inter Display. In all other fonts, including the Gnome default font Cantarell and Inter Variable text in the bold variant in rendered washed out (but only bold text, standard text is rendered perfectly fine).

Attached is a screenshot for the application Kasts, when the system font is set to Cantarell 11 and where the bold text looks blurry (it doesn't matter whether you install it from Flathub or the Arch Repo).

Another screenshot shows blurry bold font when using GNOME UI 11: https://gitlab.gnome.org/-/project/32009/uploads/3e318ae92061f1c3ad6507993035edac/Gnome_ui_Screenshot_from_2024-07-22_19-08-25.png

Another screenshot shows blurry bold font when using Inter Variable 11: https://gitlab.gnome.org/-/project/32009/uploads/fbe13bc9c781c7022063e979f04e661c/Inter_Variable_Screenshot_from_2024-07-22_19-07-55.png

For comparison, crisp and sharp when using Roboto / Noto Sans:

Here is a screenshot with the font set to Roboto 11. No blurry bold font: https://gitlab.gnome.org/-/project/32009/uploads/079ae44fa445aee844c6dc63e1da2371/Roboto_Screenshot_from_2024-07-22_18-58-32.png

Here is a screenshot with the font set to Noto Sans 11. No blurry bold font: https://gitlab.gnome.org/-/project/32009/uploads/20ea5608726aa55b923077e061abff1f/Noto.png

Kasts is only an example. Some other QT applications which are affected:
MusicBrainz Picard
KWeather
Nextcloud Desktop
Itinerary
KDevelop
…

On the AUR there is fix at least for Cantarell with the package cantarell-static-fonts (https://aur.archlinux.org/packages/cantarell-static-fonts). A user commented already back in 2022: "This package fixes ugly bold fonts in Qt apps". But this fix is only for Cantarell, so every other font still has the issue of having bold blurry text.

This issue has been discussed at other places, including https://gitlab.gnome.org/Teams/Design/initiatives/-/issues/152.
The relevant comment section starts at https://gitlab.gnome.org/Teams/Design/initiatives/-/issues/152#note_2180348.

One user over there might have a solution for this problem: "This does seem to be an issue with the Qt toolkit or the app requesting the wrong font weight, rather than an issue with the font itself. Looks like it's using "Black" (900) rather than "Bold" (700)." (Source: https://gitlab.gnome.org/Teams/Design/initiatives/-/issues/152#note_2180545)

Other places where this issue has been discussed, without any satisfying conclusion:
https://gitlab.gnome.org/GNOME/gnome-ui-font/-/issues/2#note_2178804
https://bbs.archlinux.org/viewtopic.php?id=295897 (with more screenshots - It is marked as "[SOLVED]", but the issue still persists)