One interesting tidbit.

If I'm signed in, I can't click on any buttons/links on the broken page.

If I open the page in a private browser window, I can click on them again.

this post is working fine for me 

another example

https://carkiller.com/scottykilmer/qa/car-reliability-according-to-consumer-reports/

it seems to be happening every few days now. This time, the only unusual element was the youtube video link embed. That seems to be a common thread among all these broken posts.

I've been looking at the source.

It seems the malformed tag

<p>/p&gt;</p>

is placed outside of

<div class="wpforo-post-content">

Seems like it shouldn't even be there.

If I'm not mistaken, that's not post content. That's PHP generated HTML