AJ from Google quietly announced in the Google Web Search Help forums that Google is dropping the custom date range search filter specifically on mobile searches.

You are able to access this feature by doing a search on your mobile device and scrolling the search filters below the search box from left to right and then by clicking on search filters. You can then see the time filter. In there is currently a custom date range, that is going away soon.

The “custom range” feature will remain on desktop, but Google is removing it from the mobile version.

AJ wrote:

Google keeps dropping more and more search filter options, so this should come as no surprise.

Forum discussion at Google Web Search Help.