Keep in mind that carbon dioxide is almost 3x heavier than methane. Part of the reason Venus has "so much" CO₂ is because all the lighter gasses have been deple

Keep in mind that carbon dioxide is almost 3x heavier than methane. Part of the reason Venus has "so much" CO₂ is because all the lighter gasses have been depleted. (But yes, Venus is hard to satisfactorily explain, regardless of whether you accept the article's conclusions at face value.)