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.
const scale = Util.singularValueDecompose2dScale(transform);
  
  
  scale[0] = Math.fround(scale[0]);
  scale[1] = Math.fround(scale[1]);
  const actualScale = Math.fround(
    (globalThis.devicePixelRatio || 1) * PixelsPerInch.PDF_TO_CSS_UNITS
  );
  if (interpolate !== undefined) {
    
    return interpolate;
  } else if (scale[0] <= actualScale || scale[1] <= actualScale) {
    
    return true;
  }
  
  return false;
}
const LINE_CAP_STYLES = ["butt", "round", "square"];
const LINE_JOIN_STYLES = ["miter", "round", "bevel"];
const NORMAL_CLIP = {};
const EO_CLIP = {};
class CanvasGraphics {