Attach (recommended) or Link to PDF file here:
https://s3.eu-west-1.amazonaws.com/scai-dev.website.com/tmp/8ab8b56a-fa91-11eb-8d74-0242ac110004.pdf

Hi,
Please see an incorrect canvas rendering for the following document - page 9 specifically. It reproduces on https://mozilla.github.io/pdf.js/web/viewer.html (tried with Chrome). Other pages in this document look pretty much the same but the problem is on page 9 only.

Original screenshot:
![image](https://user-images.githubusercontent.com/23075641/129066656-7bb2fb56-2b88-4f40-8e67-b95bdeb9e521.png)


PDF JS:

![image](https://user-images.githubusercontent.com/23075641/129066734-56503a5c-413c-49c1-9e1c-470da3a642ed.png)

if (hasBackdrop) {
      composeSMaskBackdrop(maskData.data, r0, g0, b0);
    }
    composeFn(maskData.data, layerData.data, transferMap);
    maskCtx.putImageData(layerData, 0, row);
  }
}
function composeSMask(ctx, smask, layerCtx) {
  const mask = smask.canvas;
  const maskCtx = smask.context;
  ctx.setTransform(
    smask.scaleX,
    0,
    0,
    smask.scaleY,
    smask.offsetX,
    smask.offsetY
  );
  genericComposeSMask(
    maskCtx,
    layerCtx,
    mask.width,
    mask.height,
    smask.subtype,
    smask.backdrop,
    smask.transferMap
  );
  ctx.drawImage(mask, 0, 0);
}
function getImageSmoothingEnabled(transform, interpolate) {