A few weeks ago we weren't checking the slug for correctness. So https://community.nodebb.org/topic/2647/anythinghere was working. But if you had images in the topic in the form of !(/no/url) this was causing an api call to the topic and loading the entire topic to solve that we started checking the slug.
If we can find a solution to that image problem we can go back to ignoring the slug.
Ah right, that makes sense.