I think I've seen this before, when a version contained a (security?) flaw that was spotted very shortly after release.
If it's a moderately serious fault and your download logs say only a handful of people have downloaded the release, it's probably better and easier to pull the release instead of leave people with it and have to rush a patch.
I am completely guessing what Atlassian might have done here, but I know a couple of development organisations have done that, including one I worked for at the time. Also, if you have highly automated release processes, you can find trigger-happy people release things a little too early (yes, "continuous deployment", I am looking at you...)
As Joao mentioned, we discovered a critical bug in Confluence 5.2.4 related to page restrictions. Due to this bug, Confluence 5.2.4 is no longer available for download. You can find more information about this in the knowledge base article Joao linked to.
Do you use templates with Confluence? Take part in a remote 1-hr workshop. You'll receive USD $100 for your time! We're looking for people to participate in a remote 1-hr workshop...
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