Conditionals inside hook

Hi

Hope you can help me out a little here, i'm trying to show a cf7 form inside a hook on a specific category. The form shows but somehow i keep breaking the sidebar which goes below the post while on desktop. Thanks !

  add_action ( 'generate_after_entry_content', 'sommar_bookings' );
function sommar_bookings() {
if ( in_category( 'sommarlov-categ' ) ){ ?>
  <?php
echo do_shortcode( '[contact-form-7 id="2857" title="Booking form"]' );
  ?>

<?php }
}