You're right the related articles stickied at the bottom is super-distracting, it draws the eye, and has to be dealt with before you can continue reading. It's an interruption plain an simple - not as bad as a layered modal - but it still introduces an element of
work to the reading experience.
The really frustrating thing is it's for related articles and it's shown first thing on the page. How about giving me a god damn minute to read the article I clicked on before prompting me to read something else. Related articles are fine. But how about putting them at the bottom of the page? I guess this is an interface a team of geniuses creates when they optimize for engagement instead of content.
This is definitely an anti-pattern.