This is a regression from #12864. The underscore is now too thin when the document is zoomed in.

URL: https://github.com/mozilla/pdf.js/files/2321540/issue6127.pdf
PDF.js 2.7.526: https://i.imgur.com/T4mIpct.png
PDF.js 2.7.510: https://i.imgur.com/nbwEpGT.png
Adobe Acrobat Reader DC 2020.013.20074: https://i.imgur.com/wDFBf3R.png

The screenshots were taken at 400% zoom.
PathType.FILL
      );
      needRestore = true;
    }
    const intersect = this.current.getClippedPathBoundingBox();
    if (this.contentVisible && intersect !== null) {
      if (this.pendingEOFill) {
        ctx.fill("evenodd");
        this.pendingEOFill = false;
      } else {
        ctx.fill();
      }
    }
    if (needRestore) {
      ctx.restore();
    }
    if (consumePath) {
      this.consumePath(intersect);
    }
  }
  eoFill() {
    this.pendingEOFill = true;
    this.fill();
  }
  fillStroke() {
    this.fill(false);
    this.stroke(false);
    this.consumePath();
  }
  eoFillStroke() {