5e88f15 created the issue

The Cyberduck Help menu has the item "Cyberduck Help", also available with cmd-? .
This menu item opens the page: https://cyberduck.io/help/

That page says that the documentation is maintained in a wiki.
And it nicely provides a button labeled "Cyberduck Wiki".
But that button just links back to that same page.

I eventually stopped clicking and googled up this page: https://trac.cyberduck.io/wiki/help/en
I assume that is the place the web page (and maybe even the menu item) meant to link to.