SV-33917 repro: 交付申請書 (blob PDF in about:blank popup)

Replicates kasegupower-total.pref.kagoshima.jp: on click the opener does window.open(''), writes a "添付資料を生成しています…" loader into the popup, fetches the PDF with progress, builds a Blob, then calls popup.location.assign(URL.createObjectURL(blob)).
Expected bug: attempt #1 opens in SafeDocs, attempt #2 (same isolated session, after closing the first popup) shows the "Document or File Download Policy Restriction" block page (download_cancelled reason_code 3).

PDF source fetch kagoshima_blob_pdf.php with progress (replica) generate in JS JS size (MB) fetch URL

Blob / navigation Blob type Navigation revokeObjectURL poll popup.closed (site does this)

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