update redirects in yoast when changing from date based permalinks to just post name

yoast_redirect_fixer.php

<?php

$option_value_export_plain = file_get_contents('export_plain.txt');
$option_value_base = file_get_contents('base.txt');

$export_plain = unserialize($option_value_export_plain);
$base = unserialize($option_value_base);

$new_export_plain = [];

foreach ($export_plain as $k => $redirect) {
    $new_url = preg_replace("/([0-9]{4})\/([0-9]{2})\/([0-9]{2})\//", "", $redirect['url']);
    $new_key = preg_replace("/([0-9]{4})\/([0-9]{2})\/([0-9]{2})\//", "", $k);

    $new_export_plain[$new_key] = [];
    $new_export_plain[$new_key]['url'] = $new_url;
    $new_export_plain[$new_key]['type'] = $redirect['type'];
}

foreach ($base as $k => $redirect) {
    $new_origin = preg_replace("/([0-9]{4})\/([0-9]{2})\/([0-9]{2})\//", "", $redirect['origin']);
    $new_url = preg_replace("/([0-9]{4})\/([0-9]{2})\/([0-9]{2})\//", "", $redirect['url']);

    $new_base[] = array(
        'origin' => $new_origin,
        'url' => $new_url,
        'type' => $redirect['type'],
        'format' => $redirect['format']
    );
}

file_put_contents('fixed_export_plain.txt', serialize($new_export_plain));
file_put_contents('fixed_base.txt', serialize($new_base));