Remove unnecessary Data sources

<?php

add_filter( 'facetwp_facet_sources', function( $sources ) {
    foreach ( $sources['custom_fields']['choices'] as $key => $value ) {
        if ( 0 === strpos( $value, '_stcr' ) ) {
            unset( $sources['custom_fields']['choices'][ $key ] );
        }
    }
    return $sources;
});