The work flow in a 3.11 site for doing a site admin search, then going elsewhere:
<311site>/admin/search.php?query=force+user

Various settings appear
Click on Save changes
On same search page, you then click on breadcrumb Site administration to return to full site admin pages

On 4.0 site <40site>/admin/search.php?query=force+user
Various settings appear BUT with site admin tabs still visible above...
Click on Save changes
On same search page, you then have the new site admin tabs above BUT they all still have the search param as part of the tab URL, so you're clicking on them but still stuck on the same page!!! This is not expected at all.

In fact, you have to click on the top top nav link - Site Admin to escape.

Testing
Go to Site admin
Type in a phrase into site admin "Search" box, such as "force user"
Click on Save changes
Click on the Users tab
Expect to go to the Users page, but in fact return to the search results page for your phrase.