Where do you enable the Search as feature for an incident?
Contextual search is a search technology that focuses on the context of the query as well as the intent of the user in order to fetch the most relevant set of results. Contextual search displays related results within a form or record producer based on the text you enter in a field.
https://www.servicenow.com/docs/bundle/yokohama-platform-administration/page/administer/contextual-search/concept/c_ContextualSearch.html