Closing the a nonmodal dialog, makes the main window minimized

Question

Refer to this post https://prismlibrary.com/docs/wpf/dialog-service.html

1. Show a dialog via the following code

_dialogService.Show("MyDialog1", new DialogParameters($), r => { });

2. Move another Window of some other process over the Shell window(e.g MainFrame) of testing prism project. and "MainFrame" is hidden behind.
3. Click the the icon of MainFrame in the taskbar to bring "MyDialog1" and "MainFrame" to topmost, they become visible.
4. Close MyDialog1, then observe.
5. When close "MyDialog1", it is expected only to close "MyDialog1" and "MainFrame" should be stay shown normally, but observed that, the "MainFrame" is minimized unexpectedly.

Tested with Prism of 8.0.0.1850, this issue still exists since prism 6 How to improve the behavior of show nonmodal dialog?