Recently I made an edit in this question in Literature SE. The added part is a link inside a tag:

<sup>
The mot was made by mathematician Poincaré in his essay [The future of mathematics](https://mathshistory.st-andrews.ac.uk/Extras/Poincare_Future/): "Mathematics is the art of giving the same name to different things."  
Follow up: [Is poetry the art of giving different names to the same thing?](https://literature.stackexchange.com/q/5220/1015)</sup> 

This is how it renders:

I'm pretty sure that it should have worked in the past, or else I wouldn't do it at the first place. I'm not sure if this the result of switching to CommonMark or not.