Freeciv

Dean Brown wrote in #note-1:

This may not help much - I have finally been able to (with great difficulty) build a Qt-6 on my Mac. It's Qt-6.7, and there is a bad display bug on the main map, which is also seen in the city dialog. Screenshot attached.

This one seems like svg flag is not drawing. I suspect that your Qt build or installation has issues with the svg module.

If one loads theme mid-game it works, including loading first another theme and then default "NightStalker" again.

This is likely a Qt bug we can do nothing about but to wait them to fix it.