Attach (recommended) or Link to PDF file here:
[Scan-to-Mail-PDF1_(1).pdf](https://github.com/mozilla/pdf.js/files/6876708/Scan-to-Mail-PDF1_.1.pdf)

Configuration:
- Web browser and its version: Firefox Developer 91.0b7 (64-Bit)
- Operating system and its version: Windows 10 (21H1)
- PDF.js version: 2.10.339 (also tested with the online demo, Version 2.11.5)
- Is a browser extension:

Steps to reproduce the problem:
1. Open the attached pdf
2. Scroll to page 3

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/7944797/126957487-cc7a2d19-adfb-42e4-9809-74e1a7a85048.png)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/7944797/126957351-29aebb4d-eadd-4273-b69d-530b9060c12c.png)




changedHorizon[0].start = boundary.y1;
      changedHorizon.unshift({
        start: horizon[i].start,
        end: boundary.y1,
        boundary: horizon[i].boundary,
      });
    }
    if (boundary.y2 < horizon[j].end) {
      changedHorizon[changedHorizon.length - 1].end = boundary.y2;
      changedHorizon.push({
        start: boundary.y2,
        end: horizon[j].end,
        boundary: horizon[j].boundary,
      });
    }
    
    
    
    for (q = i; q <= j; q++) {
      horizonPart = horizon[q];
      affectedBoundary = horizonPart.boundary;
      if (affectedBoundary.x2New !== undefined) {
        continue;
      }
      let used = false;
      for (
        k = i - 1;
        !used && k >= 0 && horizon[k].start >= affectedBoundary.y1;
        k--
      ) {