<li class="comment-list-item" id="comment-<%= comment.id %>">
  <h4 class="comment-list-item__headline"><%= h(comment.author) %> / <span class="comment-list-item__headline-date"><%= display_comment_timestamp(comment) %></span></h4>
  <%= comment.html %>
  <div class="comment-list-item__report-link"><%= report_comment_link(comment) %></div>
  <%- unless comment.published %>
    <div class="spamwarning"><%= t(".this_comment_has_been_flagged_for_moderator_approval") %></div>
  <%- end %>
</li>


<li class="comment-list-item" id="comment-<%= comment.id %>">
  <h4 class="comment-list-item__headline"><%= h(comment.author) %> / <span class="comment-list-item__headline-date"><%= display_comment_timestamp(comment) %></span></h4>
  <%= simple_format(comment.html) %>
  <div class="comment-list-item__report-link"><%= report_comment_link(comment) %></div>
  <%- unless comment.published %>
    <div class="spamwarning"><%= t(".this_comment_has_been_flagged_for_moderator_approval") %></div>
  <%- end %>
</li>


Use simple_format on comments to turn line breaks to new lines / paragraphs.
Use simple_format on comments to turn line breaks to new lines / paragraphs.