The post Don't show “removed from [site name] for reasons of moderation” for self-deleted posts is marked status-completed and if I understand it correctly, if a question was self-deleted then users without privilege to see deleted posts should get the message "This question was voluntarily removed by its author."
On Mathematics Stack Exchange, there was recently this question: Given $N$ integers on a circle , what will be the minimum pair sum? I am shown information that it was "deleted by user668959" and I see the same information in the revision history and timeline. Yet when I display the same question while not logged in, I get "This question was removed from Mathematics Stack Exchange for reasons of moderation." (I am also shown that the question had one close vote - I am not sure whether this could influence the result.) For users who cannot view this question here is a screenshot.
Here is what I get while not logged in:
I'll add that the discrepancy was pointed out to me in comments on this Meta MathOverflow discussions: Rules for deleting one's own question.
I have tried to check one self-deleted question of my own and one by another user. On those questions I got the message "voluntarily removed by its author" when viewing them while not logged in.