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.
if (!this.contentVisible) {
      return;
    }
    const ctx = this.ctx;
    const width = img.width,
      height = img.height;
    const glyph = this.processingType3;
    if (COMPILE_TYPE3_GLYPHS && glyph && glyph.compiled === undefined) {
      if (width <= MAX_SIZE_TO_COMPILE && height <= MAX_SIZE_TO_COMPILE) {
        glyph.compiled = compileType3Glyph({ data: img.data, width, height });
      } else {
        glyph.compiled = null;
      }
    }
    if (glyph?.compiled) {
      glyph.compiled(ctx);
      return;
    }
    const mask = this._createMaskCanvas(img);
    const maskCanvas = mask.canvas;
    ctx.save();
    
    
    ctx.setTransform(1, 0, 0, 1, 0, 0);
    ctx.drawImage(maskCanvas, mask.offsetX, mask.offsetY);
    ctx.restore();
    this.compose();
  }
  paintImageMaskXObjectRepeat(