Dec 22 2020
Dec 15 2020
Nope, same as without "unhide=1".
Sep 20 2020
I cannot see blocks on Special:Contributions. I am viewing Special:Log/block. The "show" link goes to Special:RevisionDelete: https://ru.wikipedia.org/w/index.php?title=Special:RevisionDelete&target=Special%3ALog%2Fblock&type=logging&ids=33182256 (the actual link has localized names for the namespaces and the RevisionDelete page) So yes, it seems that it is the same as "change visibility" but with different supposed outcome.
If I manually replace RevisionDelete by Undelete in the URL (by the analogy with the URLs for viewing the deleted revisions, see below), I get an even more cryptic error message: "Permission error. You do not have permission to view a page's deleted history, for the following reason: The action you have requested is limited to users in one of the groups: Administrators, Arbitration committee members." (Note that actually I am an Arbitration committee member.)