Enable light theme for Private browsing windows?

Today I updated Firefox, now v106.01, on Windows. There was an option to add the Private browsing icon to the task/toolbar which I've wanted for a long time. When I clicked on it, the Private browsing window opened with a dark theme. Way too hard to read! I don't use dark theme on my PC for anything because I can't see some of the elements on my page.

I went looking for an option to return it to the auto system light theme which is my default for all my Firefox browsing. I couldn't find anything addressing this issue. I tried Colorways which could offer a bearable soft theme, but it also changed the appearance of my home browser page. I had to reset.

There ought to be an option for light theme on both home page and Private browsing. For those who prefer the dark theme, have an option for dark theme. You do this for many other features of Firefox letting us choose our browsing experience. Do the same here. Default to light and have the option to click for dark. Don't just force the dark theme on all of us.

So I have the same question: How do I enable the light theme/turn off the dark theme for Private browsing windows?

Thanks so much cor-el, this is exactly what I needed!

I'm surprised this setting isn't editable via the Preferences UI, seems like an accessibility setting people should have easy access to.