title: Regex in Aggregation not returning documents in right order
body: <p>I am using the aggregation below to search user by <code>user_name</code> and <code>full_name</code> fields.</p>
  <pre><code>[{
        $match: {
          $or: [
            {
              user_name: {
                $regex: q.trim(),
                $options: 'i',
              },
            },
            {
              full_name: {
                $regex: q.trim(),
                $options: 'i',
              },
            },
          ],
          initialized: true,
          _id: {
            $nin: [userId, ...blockedUsers],
          },
        },
      }]
  </code></pre>
  <p>The result for the above query with <code>q='s'</code> is:</p>
  <pre><code>[
  {
    &quot;_id&quot;: &quot;62073c243c74c43befc9249f&quot;,
    &quot;user_name&quot;: &quot;carolina&quot;,
    &quot;full_name&quot;: &quot;Caroline Forbes&quot;,
    &quot;initialized&quot;:true
  
  },
  {
    &quot;_id&quot;: &quot;62073d0a3c74c43befc924e9&quot;,
    &quot;user_name&quot;: &quot;stefan&quot;,
    &quot;full_name&quot;: &quot;Stefan&quot;,
    &quot;initialized&quot;:true
  },
  {
    &quot;_id&quot;: &quot;62073d0a3c74c43befc924e9&quot;,
    &quot;user_name&quot;: &quot;steve&quot;,
    &quot;full_name&quot;: &quot;Steve&quot;,
    &quot;initialized&quot;:true
  }
  ]
  </code></pre>
  <p>As you see the order in which documents are coming is not correct <code>carolina</code> should be below <code>stefan</code> and <code>steve</code>
  Working example: <a href="https://mongoplayground.net/p/RPL_4mpe1DS" rel="nofollow noreferrer">https://mongoplayground.net/p/RPL_4mpe1DS</a></p>