bef-hidden.html.twig in Better Exposed Filters 8.4

{#
  Themes Views' default multi-select element as hidden input elements.

  Available variables:
    - hidden_elements: Array of hidden input elements for all possible filter
      options.
    - selected: Array of selected values.
#}
{% for value, hidden in hidden_elements %}
  {% if value in selected %}
    {{ hidden }}
  {% endif %}
{% endfor %}