STR:
  - Go to https://mozilla.github.io/pdf.js/web/viewer.html
  - Click on "Open File" and open a pdf

The `Download` button and the `Current view` one just disappear.
I can reproduce this bug with Firefox nightly, Chrome stable and Epiphany on debian.
if (PDFViewerApplication.overlayManager.active) {
    return;
  }
  let handled = false,
    ensureViewerFocused = false;
  const cmd =
    (evt.ctrlKey ? 1 : 0) |
    (evt.altKey ? 2 : 0) |
    (evt.shiftKey ? 4 : 0) |
    (evt.metaKey ? 8 : 0);
  const pdfViewer = PDFViewerApplication.pdfViewer;
  const isViewerInPresentationMode = pdfViewer?.isInPresentationMode;
  
  
  if (cmd === 1 || cmd === 8 || cmd === 5 || cmd === 12) {
    
    switch (evt.keyCode) {
      case 70: 
        if (!PDFViewerApplication.supportsIntegratedFind && !evt.shiftKey) {
          PDFViewerApplication.findBar.open();
          handled = true;
        }