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.
} else {
            for (let i = currentIndex + 1, ii = numPages; i < ii; i++) {
              const currentId = yArray[i],
                expectedId = yArray[i - 1] + 1;
              if (currentId > expectedId) {
                return expectedId - currentPageNumber;
              }
            }
          }
          
          if (previous) {
            const firstId = yArray[0];
            if (firstId < currentPageNumber) {
              return currentPageNumber - firstId + 1;
            }
          } else {
            const lastId = yArray[numPages - 1];
            if (lastId > currentPageNumber) {
              return lastId - currentPageNumber + 1;
            }
          }
          break;
        }
        break;
      }
      case ScrollMode.HORIZONTAL: {
        break;
      }
      case ScrollMode.PAGE:
      case ScrollMode.VERTICAL: {