Because our river layer still consists of many segements stored as separate features with their own start and end node we need to dissolve the layer first, so it becomes one feature.
1. In the main menu choose Vector | Geoprocessing tools | Dissolve...
2. In the Dissolve dialogue choose the Kirpich_data river layer as Input layer, don't choose a dissolve field and save the layer to the Kirpich_data GeoPackage with the name river_dissolved and click Run.
3. Click Close after processing.
4. Copy the style from the Kirpich_data river layer and remove that layer.
5. Check the attribute table.