This is a remnant of a voice command or a status message. Historically, when you triggered Siri on an older iOS device, the screen would display “Searching for...” followed by your spoken query. The hyphen and trailing space suggest a user manually typed what they thought Siri was processing—or copied a notification fragment.
In the age of voice assistants and hyper-specific search queries, we often type (or speak) things into our devices that lead us down unexpected rabbit holes. One of the most curious, fragmented, and misunderstood search phrases emerging from user logs is: Searching for- siri xxx in-All CategoriesMovies...