Missing icons in second and subsequent Falkon windows

[probonopd]

Missing icons in second and subsequent Falkon windows.

Only then QtPlugin is used and QT_QPA_PLATFORMTHEME=panda is set. Maybe the issue is there.

[probonopd]

We need to check whether this happens with panda-qt5-plugin too.

[probonopd]

Interestingly, this does not happen if one goes to Preferences in Falkon and clicks "Apply". From there on, new Falkon windows are no longer missing their icons. What gives...