This is on a pretty complex site so I have no idea where to start looking for the cause of this behavior.
I have installed the Publish Content module, which creates a little "publish" or "unpublish" tab along with "view" and "edit" on each node, for users that have permission to publish or unpublish content.
When I click on "publish" or "unpublish" once, the expected behavior follows. But if I double-click on that tab (and only that tab – others don't do this), then instead of reloading the node, it takes me to my user page.
I tried disabling the devel module but that didn't help. It happens on multiple content types, and as multiple different users with different roles, including user 1.
I have a couple of rule-based redirects in place, but they're only for specific roles and they're only triggered on particular actions (such as login). And none of them redirect to the user's own page.
I have no idea where to start debugging this.