This is not a related search; it is a context search, and it has been defined here:
the image you shared is Contextual search and is handled using UI macro and is added on incident form as formatter. how that UI macro works we are not sure as it's coming from platform level.
this KB explains it -> how the setup is done
more links for reference here
In Short:
-> Contextual Search uses predefined contexts and sources to generate queries from fields like Short Description on the Incident form.
-> It retrieves results from configured Knowledge Bases or Catalog Items.
-> You can map Incident fields to Knowledge article categories to filter results by relevance, such as service desk or business unit.
If my response helped please mark it correct and close the thread so that it benefits future readers.
