Two windows will be displayed

I have a question about Unity windows.

When I launched Unity recently, it has two screens.
It used to be one window, but
Two windows, a normal screen and a plain white window, will appear on their own.

Two projects are not open.
There are two per project.

It will also be a new empty project.

There is no problem if the white screen is left behind.
However when I change with the values ​​in the inspector, the white screen sometimes comes to the front, which is very disturbing.

Please tell me who knows how to fix it.

・Unity2020 (&2019)



Restore the layout to the default and restart.

After that, I made a layout of my choice and saved it.
It no longer occurs.