It feels like there are a thousand ways to find the information you need these days, but folks set in their workflow may rely on at most one or two of them to get the job done. Unfortunately for fans of "basic" search, we recently lost a pretty useful one: Contacts no longer appear in autocomplete when searching via the Google app or Search widget.
We don't know precisely when the feature was removed, though Google actually made a formal announcement of the change in its community help pages/support forums around two months back. Unfortunately, the medium chosen made the company's acknowledgment of the change mostly silent. Depending on how it was disabled, the feature may have also persisted for some past that point — Google slowly rolls out these sorts of changes.
No results (left) for contacts associated with your account (middle) searching from the Google Widget or Google app. They'll still appear in actual search results (right), though. Below is how they used to appear in autocomplete.
As a result of the change, the "from your contacts" shortcuts no longer appear in autocomplete when searching via the Search widget or Google app. Though contact details will still appear when you actually submit the search in your personal results, they require an internet connection to work, may integrate with fewer apps, are slower, and you may have to scroll a little to find them. (I.e., results from your contacts are still there if you actually make the search, they just have more limitations.)
Contact details still surface as expected searching via the Assistant, though.
There's been a lack of parity between the different methods Google offers for search in Android. With most of its attention these days going to the Assistant, and full functionality there preserved, you could also just switch to searching for contact details there, assuming you have elected to use the Assistant on your phone.
Maybe it's time to re-think the Search widget entirely?
There's also a larger question to be asked when it comes to the general utility of search via the Google app and widget, given that Google appears to be cutting functionality. If Google's going to strip features out of the search widget, maybe it should just be replaced entirely by a dedicated Assistant widget? For some, that button on the right side is all it's used for, anyway.