Those lines in the VST3 wrapper are there to set the plug-in editor to the correct size after the setScaleFactor() call. Since prevEditorBounds will always be in terms of logical pixels we can call setBounds() and it’ll correctly scale the native window, which will be in terms of physical pixels on Windows, after the scale factor has been updated. I’d be hesitant to remove them since they are needed for certain DAWs to behave correctly on Windows.
I’m not able to reproduce this with JUCE AudioPluginDemo - I’ve built the standalone target on Windows and am moving it between screens with different scale factors but it scales correctly and there is no DropShadower crash occurring. Can you provide some example code that reproduces the issue?