Optionally use instead:
qdbus org.kde.kded6 /kded org.kde.kded6.unloadModule "appmenu" && QT_AUTO_SCREEN_SCALE_FACTOR=1 davinci-resolve & sleep 20 && qdbus org.kde.kded6 /kded org.kde.kded6.loadModule "appmenu"
in order to also have DaVinci Resolve adhere to Global Scaling (for pixel perfect renderings you will need to make sure all monitors use the same scale factor – this is true whether or not QT_AUTO_SCREEN_SCALE_FACTOR=1 is set)