Blank Private Browsing Page

This extension is very nice, but it's flawed and when you open multiple private windows in a row you get a purple page.

Works well. I'm on Firefox's 75 and 76 as I write this. After installing, you must exit all running firefoxes of course. This extension is NOT about automatically going to private mode, it is about getting rid of that loud screaming purple page that announces to everyone around who is looking at your screen that you are about to go into online banking or whatever. Also, as it installs, don't forget to switch on the new setting to "allow it to run on private windows" - by definition, that's the ONLY time this thing needs to work! If you missed that at installations, it's easy enough (at the moment) to find that setting for each addon in the addons page. This item should be put into the "Recommended Extensions" program. Is the nazi-half of Mozilla development teams holding it back, or is it just too much trouble? EDIT: doesn't work when you click [+] for a new tab! Still get a purple. I suppose the "new tab" URL needs setting somewhere?