I am not convinced that this is a problem for dark matter at all. (The Forbes article is beyond an ad wall.)
But if it is, more often problems go away when the observation is scrutinized. For example, this hinges on the light measurements instead measuring ordinary matter. (The type of measurement that dark matter critics for reasons of their own calls ‘placeholders’.) In this case light can be extinguished by galactic gas clouds or by the ISM on the way, et cetera.
In sum: The title? Click bait.