How to remove the error message that comes out in the input - php

Hello everyone I have a small problem with the input, I get an error message in the input, I've been looking to resolve but I have not obtained results.

I attached an image of the error that shows me.

Here I attach the code.

  <?php
 include 'conexion.php';
  ?>

 <form action="buscador.php" method="get">
 <input type="text" name="palabra" placeholder="buscar aqui.." value="<?php  echo ($_GET["palabra"]); ?>"  />
  <input type="submit" name="buscador" value="Buscar" id="buscar" />

 <style type="text/css">
   #buscar{
    display: none;
         }
</style>

</form>
<?php 

if(isset($_GET['buscador'])){

$buscar = $_GET['palabra'];

if (empty($buscar)){
echo "No se ha ingresado ninguna palabra";
}
else
{

$sql = "SELECT * FROM registro WHERE nombre LIKE '%$buscar%'";
$result = $conexion->query($sql);

$total = mysqli_num_rows($result);

if ($row = mysqli_fetch_array($result)) {

echo "Resultados para: $buscar";
?>
<br>
<?php
echo "Total de resultados: $total";

do {
 ?>
<br>
<br>
 <a href="<?php echo $row['link'] ?>">(nombre: <?php echo $row['nombre']; ?>)
 </a>

<?php
}
while ($row = mysqli_fetch_array($result));
}
else
{
echo "No se encontraron resultados para: $buscar";
}
}
}
?>