I’m still not further … I found the following code, but it only shows “array” …. really stupid
$filamente = get_field( 'filament' );
foreach($filamente as $filament):
$filament_fields = get_field('$filament', $filament);
if( $filamente_fields ):
$filament_fields_slugs = array_column($filament_fields, 'slug');
$data_filament_slugs = implode(', ', $filament_fields_slugs);
endif;
endforeach;