Force min date of “today” for date picker

<?php

// Add to your (child) theme's functions.php
// replace "YOUR_FACET_NAME" with your *actual* facet name

add_filter( 'facetwp_render_output', function( $output ) {
    $output['settings']['YOUR_FACET_NAME']['range']['min']['minDate'] = date( 'Y-m-d' );
    return $output;
});