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.
PixelsPerInch.PDF_TO_CSS_UNITS;
    let scale = 0;
    switch (destArray[1].name) {
      case "XYZ":
        x = destArray[2];
        y = destArray[3];
        scale = destArray[4];
        
        
        
        
        x = x !== null ? x : 0;
        y = y !== null ? y : pageHeight;
        break;
      case "Fit":
      case "FitB":
        scale = "page-fit";
        break;
      case "FitH":
      case "FitBH":
        y = destArray[2];
        scale = "page-width";
        
        
        if (y === null && this._location) {
          x = this._location.left;
          y = this._location.top;
        } else if (typeof y !== "number" || y < 0) {