This bug report refers to self-compiled Falkon in version 24.08.02 in the Linux operating system Tuxedo OS 3.

1. In KDE System Settings > Text & Fonts > Fonts, change the default font from "Noto*" to a different font via the "Adjust all fonts" button. In my KDE font settings, all font display types like "General", "Small" and "Fixed width" are set to that other font, I only kept the "Fixed width" font type to the font "Hack".

For setting these settings to a different font than the default font in KDE I used the B612 font, which can be downloaded from

https://github.com/polarsys/b612

I installed the B612 font in the KDE System Settings via > Text & Fonts > Font Management.

2. Log out of KDE and login into KDE again.

3. Start Falkon, Edit menu > Preferences > Fonts: Change all fields there to "B612" or "B612 Mono", except for the font type fields "Cursive" and "Fantasy", which I kept to the default values, i. e. to "Z003 [urw]" and "D050000L [urw]". Below these font-type-related fields, put all font size fields to "16".

4. Restart Falkon.

5. In Falkon, open https://www.deutschlandfunk.de

6. Compare the look of the font used for displaying the Falkon menu headers in the Falkon GUI with the look of the font which is used to display the text content on https://www.deutschlandfunk.de - you will notice a difference, although there shouldn't be a difference, if I am not wrong.

7. You can notice the same if you open the same URL in Konqueror (in version 24.08.1, installed as a *.deb package provided by Tuxedo OS), before that having changed in Konqueror the default font to "B612" via menu Settings > Configure Konqueror > Appearance > Fonts ("Standard Font", "Serif Font" and "Sans Serif Font" set to "B612") + "Minimim font size" = "11" + "Medium font size" = "13 "+ a restart of Konqueror.

8. If you open the same URL in the LibreWolf browser (in version 131.0.2-1, installed as a *deb package provided by the PPA of librewolf.net), before that having changed in LibreWolf the default font to B612 via menu Edit > Settings > "General" section to the left > "Language and Appearance" to the right > Fonts > "Default Font" = "B612", size = "16" + button "Advanced" > "Fonts for" = "Latin" + "Proportional" = "Serif" + "Serif" = "B612", "Sans-Serif" = "B612", "Monospace" = "B612 Mono" + all font size files set to "16" + option "Allow pages to choose their own fonts, instead of your selections above" unchecked.

=> then the text content on https://www.deutschlandfunk.de is displayed using the B612 font, which is in contrast to the behavior of Falkon and Konqueror .

Falkon uses QtWebengine, and I have set Konqueror to use QtWebengine, too (via the Settings menu > Configure Konqueror > "General" section to the left).

LibreWolf uses the same web browser engine like Firefox, and Firefox's and LibreWolf's web browser engine is called Gecko, that is what I can among other things see if I select another browser identification in Falkons browser identification settings.

So I guess the behavior I reported here has to do with the use of two different web browser engines, where QtWebengine seems to not behave as expected. Something which I did not report yet to the makers of "Qt", I wanted to report this behavior here first.

I attached three screenshots to this bug report. If you download them into the same folder you could view them in Gvenview as an image gallery for better comparing single letters displayed on https://www.deutschlandfunk.de in Falkon, Konqueror and LibreWolf.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Tuxedo OS 3
KDE Plasma Version: KDE Plasma 6 .1.5
KDE Frameworks Version (kf6-frameworkintegration): 6.6.0
Qt Version: 6.7.2