While some significant gains were to be had with the Fall Creators Update in relation to searches from the Start menu, adding web searches directly from Bing, it has always been a choice to enable web searches or not in Windows 10, that is until the spring update, which has broken the group policy conditions that disable it.
gHacks first discovered the bug this past weekend and noted that no matter how the three related group policy permissions are set, the web search remains enabled with Bing results showing up in the start menu. For example, a search for the German city of Dortmund returned a map, a short description, some images and other information directly from Bing.
Enterprise or Education versions of the Windows 10 spring update are reportedly not affected.
You can find the policies (in gpedit.msc) under Local Computer Policy > Computer Configuration > Administrative Templates > Windows Components > Search.
The policies are:
Do not allow web search
Don't search the web or display web results in Search
Don't search the web or display web results in Search over metered connections
Windows 10 fails to block web search results even if all three of the preferences are set to enabled. gHacks also discovered that systems running Redstone 5, the next version of Windows 10 after version 1803, has the same issue.
Luckily there's a workaround that will block web searches, should you so desire it. You can download the registry file here or create your own from the following entries.
Windows Registry Editor Version 5.00
Before applying the above fix, and upon navigating to the above registry path in the spring update (build 17133.1), those entries are completely missing from the "Search" registry key, so you can safely delete them should you want to revert.
There's every chance Microsoft will correct this error with a cumulative update, but for now here is a workaround you can use while we wait for peer feedback or a kind Microsoft developer to upvote the Feedback Hub entry for this bug to get fixed.