Why using the H2 tag does the following text lose the formatting?

I have an HTML structure as follows:

<section>
  <h1>Título</h1>
  <article>
    <h2>Sub Título</h2>
    <p>
      Texto ........
      <h2> Outro Sub </h2>
      Texto sequencia....
    </p>
  </article>
</section>

When I put <h2> Outro Sub </h2> the text then loses the stipulated formatting.

H2 was placed under the Beaches subtitle, then the following text has lost formatting.

Follow photo of what happens:

Does anyone know what might be happening?

CSS:

p{
font-size: 18px;
color: #333;
line-height: 1.6;
text-align: justify;
margin-bottom: 20px;
}