Answer
While the export runs, the browser tab itself shows a loading/spinner indicator in its favicon area (visible in both Chromium-based Edge and Chrome) — there's no separate on-screen progress bar, but this tab-level indicator confirms the export is actively running in the background. Once complete, the Excel file downloads automatically and appears in your browser's Downloads; if the export fails instead, a toast notification appears telling you it failed. You can safely open and work in other tabs while the export runs — doing so does not stop or interrupt the ongoing background export.