What? The query prompts me to search the content. I assumed I could search for any string, not just URLs. Is this only an index of websites included in the documents?

This is a bug in your site triggered by an incorrect <input> attribute (I don't recall the exact one, maybe "type" - but it affects which keyboard is shown by mobile browsers).

EDIT: Screenshot - https://i.ibb.co/dMm7Jpp/C48-EFAFB-C8-B2-4147-AC48-3-AC07584...