Blue lines left behind in console after backspacing

Question

So I have a function that lets me move a full block unicode character across the console with wasd and the arrow keys. I use this function to change the coordinates of this full block character:

public static void Render(int x, int y)
        {
            Console.Write("\b \b");
            Console.SetCursorPosition(x, y);
            Console.Write("\u2588");
        }

It works as intended, but there's something weird left behind by it every time I move the character to the right. It looks like this: Image

It leaves behind vertical blue lines when I move it to the right and I don't understand why. In the image I left, I moved it to the right, moved down, moved it further right, repeat. I would like to know why this is happening, and if there is any way to fix this. It's only graphical but it bugs me.