Fandom adds "Hot" articles to the sidebar. When new game content drops, related pages become "Hot". This means that spoilers can appear in the sidebar. This extension is very simple and does exactly what needs to be done.

OMG thank you! what an annoying "feature" that this extension fixes.

Doing god's work.

Finally. I don't know why fandom wiki decided recently to automatically open the sidebar when you visit a site for the first time.