<section class="brexit-checker__share">
  <% hidden_text = capture do %>
    <span class="govuk-visually-hidden">Share on</span>
  <% end %>
  <h4 class="govuk-heading-m">
    <%= I18n.t("brexit_checker.results.share_link_title") %>
  </h4>
  <%= render "govuk_publishing_components/components/share_links", {
    columns: true,
    links: [
      {
        href: "https://www.facebook.com/sharer/sharer.php?u=#{encoded_results_url}",
        text: hidden_text + "Facebook",
        icon: "facebook"
      },
      {
        href: "https://twitter.com/share?url=#{encoded_results_url}",
        text: hidden_text + "Twitter",
        icon: "twitter"
      },
      {
        href: "https://api.whatsapp.com/send?text=#{encoded_results_url}",
        text: hidden_text + "WhatsApp",
        icon: "whatsapp"
      },
      {
        href: "mailto:?body=#{encoded_results_url}&subject=#{I18n.t("brexit_checker.results.title")}",
        text: hidden_text + "Email",
        icon: "email"
      },
      {
        href: "http://www.linkedin.com/shareArticle?url=#{encoded_results_url}",
        text: hidden_text + "LinkedIn",
        icon: "linkedin"
      },
    ]
  } %>
</section>

<section class="brexit-checker__share">
  <% hidden_text = capture do %>
    <span class="govuk-visually-hidden">Share on</span>
  <% end %>
  <h2 class="govuk-heading-m">
    <%= I18n.t("brexit_checker.results.share_link_title") %>
  </h2>
  <%= render "govuk_publishing_components/components/share_links", {
    columns: true,
    links: [
      {
        href: "https://www.facebook.com/sharer/sharer.php?u=#{encoded_results_url}",
        text: hidden_text + "Facebook",
        icon: "facebook"
      },
      {
        href: "https://twitter.com/share?url=#{encoded_results_url}",
        text: hidden_text + "Twitter",
        icon: "twitter"
      },
      {
        href: "https://api.whatsapp.com/send?text=#{encoded_results_url}",
        text: hidden_text + "WhatsApp",
        icon: "whatsapp"
      },
      {
        href: "mailto:?body=#{encoded_results_url}&subject=#{I18n.t("brexit_checker.results.title")}",
        text: hidden_text + "Email",
        icon: "email"
      },
      {
        href: "http://www.linkedin.com/shareArticle?url=#{encoded_results_url}",
        text: hidden_text + "LinkedIn",
        icon: "linkedin"
      },
    ]
  } %>
</section>

Change share links title from h4 to h2
Change share links title from h4 to h2

The level of the heading is on a par with group headings and should be promoted for sensible markup and accessibility
