Regarding when a WPF application using the "PresentationFramework.Fluent" theme experiences a flashing window in dark mode.

I have converted 4 apps with extensive use of windows to PresentationFramework.Fluent and aside from issues already raised I am quite happy with it except that most of the time when Dark Mode windows open there is a brief flash of white before the window is drawn, this is immediately after window.Show() and before the redraw starts.
I haven't seen it mentioned here yet but an AI search describes it and the felling is that this a Windows problem rather than WPF.
This issue is an absolute show stopper as it is very jarring and widespread.
I am running the latest Windows11, an Intel Ultra 9 285k CPU and an Nvidia 4060 GPU so processing speed is unlikely an issue.
Is this widespread and will a solution be found is what I am really asking.
Would anyone like to comment.