On Firefox on macOS, almost always, the close button for these monstrosities is positioned flush right and sized exactly such that it extends merely 1 pixel lef

On Firefox on macOS, almost always, the close button for these monstrosities is positioned flush right and sized exactly such that it extends merely 1 pixel left of the scroll bar. So, to close them, you must either aim precisely for this 1 pixel sliver, or move slowly enough that the scroll bar does not appear. These days I just click Reader Mode for almost any news site. I wish I could somehow set domains to always open in Reader Mode.