We could use:
https://github.com/mozilla/pdf.js/blob/c3d08580627471432a6ad0b2fdb948df64126afa/src/display/api.js#L929

and look at bit 4.

The following pdf:
https://orimi.com/pdf-test.pdf
is not editable in neither Acrobat nor Edge nor Foxit and nor Okular.
const currentScale = pdfViewer.currentScale;
    if (previousScale !== currentScale) {
      
      
      
      const scaleCorrectionFactor = currentScale / previousScale - 1;
      const rect = pdfViewer.container.getBoundingClientRect();
      const dx = evt.clientX - rect.left;
      const dy = evt.clientY - rect.top;
      pdfViewer.container.scrollLeft += dx * scaleCorrectionFactor;
      pdfViewer.container.scrollTop += dy * scaleCorrectionFactor;
    }
  } else {
    setZoomDisabledTimeout();
  }
}
function webViewerTouchStart(evt) {
  if (evt.touches.length > 1) {
    
    
    
    
    
    
    
    
    evt.preventDefault();
  }
}
function webViewerClick(evt) {