PDFViewer.createExporter()

A PDFExporter wired to this viewer's form values and signatures. Its defaults are the viewer's export option; config overrides them. Obtain the exporter here rather than with new PDFExporter(document): it carries what the viewer holds and reports exportStarted / exportCompleted on the viewer, and an export of the whole document clears hasUnsavedChanges the moment the bytes leave the viewer — whether your upload of them succeeds is yours to track (see Saving as the user works).

const exporter = viewer.createExporter();
await exporter.download('report.pdf');