Where did the related tropes disappear to?

On the left side of the page, there was always the related tropes for the given article (as in you'd go onto the page for Dark Souls and on the side would be, say, Dark Souls/ Nightmarefuel) About a month or so ago it disappeared and I just assumed it was my computer, but I tried looking on different computers and on different web browsers and it still isn't there. What do I do?

What you are referring to is the list of subpages which others have complained about the disappearance of in the past, including in this very forum. Long story short, it's not coming back as the powers that be consider whatever use it had to be obviated by the row of icons at the top, with any subpages not represented there available from the Subpages dropdown just above it.