You have an add-on installed related to this? Mine does not look like that. It appears that the container for that is the full width, that is whatever setting you have in Style properties > Page setup > Maximum page width
Yours is considerably smaller than that and it appears to be modified by a plugin.
Ah, it's probably Andrew's Mod Panel that shows the left-side menu. And yes, I limited the width of my board. I don't know of a way to increase the width only for the mod queue.