[SOLVED] QT applications blurred pixmaps

So I have a strange problem wtih Qt applications displaying broken pixmaps :

Theme and fonts are OK but some rendered images look badly aliased like that splash screen or the checkboxes buttons.

If I display maps in QGis they are bordeline unreadable.
Kde & GTK apps have no problem, only pure qt apps.

I have tried making a new config with qt5ct unsuccessfully.

If I launch those apps as root, the proble disappears.

Any idea on this ?

Problem solved with restoring desktop scaling to 100 %