First block is exported from Illustrator and cleaned with svgo (https://github.com/svg/svgo) using "--pretty". Second block is the same svg icon this time refactored manually.

svg-differences.html

<!-- Illustrator export + 'svgo --pretty' -->

<svg xmlns="http://www.w3.org/2000/svg" preserveAspectRatio="xMidYMid" width="50" height="50" viewBox="0 0 50 50">
    <defs>
        <style>
            .cls-3 { fill: #e7e7e7; } .cls-4 { filter: url(#color-overlay-1); font-size: 26px; } .cls-5 { fill: #8d8d8d; font-size: 26px; font-family: &quot;Book Antiqua&quot;; }
        </style>
        <filter id="color-overlay-1" filterUnits="userSpaceOnUse">
            <feFlood flood-color="#8d8d8d" flood-opacity="1"/>
            <feComposite operator="in" in2="SourceGraphic"/>
            <feBlend in2="SourceGraphic" result="colorOverlay"/>
        </filter>
    </defs>
    <g id="info-normalsvg">
        <circle id="circle-1" class="cls-3" cx="25" cy="25" r="25"/>
        <text class="cls-4" x="21" y="34">
            <tspan class="cls-5">
                i
            </tspan>
        </text>
    </g>
</svg>

<!-- Hand crafted -->

<svg xmlns="http://www.w3.org/2000/svg" preserveAspectRatio="xMidYMid" width="50" height="50" viewBox="0 0 50 50">
  <g>
    <circle class="circle" cx="25" cy="25" r="25"></circle>
    <text class="text-block" x="21" y="34">i</text>
  </g>
</svg>

<style>
      .circle {
        fill: #e7e7e7;
      }

      .text-block {
        font-size: 30px;
        font-family: "Book Antiqua", serif;
        fill: #ffffff;
      }
</style>