Whenever a Cyrillic character appears in Konsole or Kate line height starts changing. Selecting lines with Cyrillic characters triggers changing height back and forth. Described also in this confirmed report for Konsole https://bugs.kde.org/show_bug.cgi?id=297390#c19 Reproducible: Always Steps to Reproduce: Open Konsole, ensure you have Oxygen Mono font (default at least in Kubuntu packages), type some lines with Latin-only characters, some lines mixed with Cyrillic. Try selecting and unselecting these lines. Actual Results: Line height changes upon appearance of a Cyrillic character. Expected Results: Line height stays the same.
Thanks for your bug report. Unfortunately we do not have the resources to maintain this font anymore and moved upstream to using the Noto font and Droid Sans Mono which also provide much better glyph coverage. We advise you do the same. Sorry.