Some headlines in Plasma widgets and normal KDE windows/dialogues are rendered badly (bad antialiasing, wrong size, too condensed) when DejaVu Sans is used as the main font. Reproducible: Always Steps to Reproduce: 1. Choose DejaVu Sans as font in the system settings 2. (additionally) antialiasing, hinting: complete Actual Results: Most of the text is rendered correctly (sharp, correct size) but some headlines (username in KMenu or month in the date/calendar widged or see "Allgemein"/"Kategorien"/"Zusätzliche Einträge" linked image) are rendered in a condensed/slim way with bad antialiasing and are too big. Expected Results: A consistent face type with clear font rendering for both normal text (this is already achieved) and headlines when using DejaVu Sans/Bitsream Vera Sans or any other font family. The same results as for the Noto Sans font is expected. This bug does not occur with other fonts like Noto Sans or Arial (I have not tested all fonts). It has been reproduced with Kubuntu 16.06 LTS (both Plasma 5.5 and 5.6, backports packages) and Manjaro 16.06.1.
Are the dialogs in question those created by Plasma (e.g. the one in your screenshot is "System Tray Settings" I think [given I don't speak German])? I also see this bug, though in my case it appears with all fonts, and is more obvious than in your case (probably something to do with running at a higher resolution). See bug 355935 for my report.
Works for me. Can you reproduce this in Plasma 5.17?
Thank you for the reminder. I cannot reproduce this bug anymore - but I don't know which of the many updates in the last years have lead to the improvement. Screenshot as a comparison: https://abload.de/img/screenshot_20200131_24ak15.png (a lot of other things have happened though: font size, positioning, etc)