Even when nothing's being modified, links are shown through spoilers when looking at the non-markdown output of a revision. This happens both when reviewing edits and when looking at the revision history like normal. And it looks weird.
Here's what it looks like when reviewing an edit (and nothing changed in the spoiler):
And here is an example of revision history where you can see this on one of my answers. Some of the spoiler blocks there were modified, so you can see what it looks like for comparison.