Index colors within ACF checkbox fields

<?php

// Add the following to your (child) theme's functions.php
add_filter( 'facetwp_index_row', function( $params, $class ) {
    if ( 'MYCOLOR' == $params['facet_name'] ) {
        $raw_value = $params['facet_value'];
        $params['facet_value'] = str_replace( '#', '', $raw_value );
        $params['facet_display_value'] = $raw_value;
    }
    return $params;
}, 10, 2 );