Firestore's pricing is not a footnote you read after shipping. It is a constraint that propagates all the way up into your schema, your query layer, and your React effects. The unit of billing is one document operation , not one query, not one byte, not one connection.
Source: [Dev.to](https://dev.to/toyama0919/firestore-bills-you-per-document-not-per-query-design-accordingly-1j1j)