{{ govuk.phaseBanner(
    phase = "beta",
    messageHtml = "This service is new – your <a href=\"#\">feedback</a> will help us to improve it."
) }}
<%= govuk.phase_banner(
    phase: "beta",
    messageHtml: "This service is new – your <a href=\"#\">feedback</a> will help us to improve it."
) %> 
<div class="gv-c-phase-banner">
    <p class="gv-c-phase-banner__content">
        <strong class="gv-c-phase-tag">beta</strong>
        <span class="gv-c-phase-banner__text">This service is new – your <a href="#">feedback</a> will help us to improve it.</span>
    </p>
</div>
{
  "phase": "beta",
  "messageHtml": "This service is new – your <a href=\"#\">feedback</a> will help us to improve it."
}