Comment 3 for bug 1699162

What happens is Dark theme sets default text color to white, so the label representing the name of the point, line will be white on a white canvas, so not visible.
To see this happens, you need to edit the style of an object and name it (by default Dr. Geo does not put name on objects).

However as wrote earlier, under the Dark theme the canvas should not be white but more like a paler grey, it will be more comfortable for the eyes.