Admin Dashboard Crash

Fixed by
– editing AdminHooks.php – replaced from line 137 to 179 with the below code.
– got back the admin dashboard
– deleted all filters
– deleted the plugin Filter Everything
– reinstalled the plugin
– recreated filters

public function checkForbiddenPrefixes()
{
    $forbiddenPrefixes  = flrt_get_forbidden_prefixes();
    $savedPrefixes      = get_option( 'wpc_filter_permalinks', [] );

    // Ensure $savedPrefixes is an array
    if (!is_array($savedPrefixes)) {
        $savedPrefixes = maybe_unserialize($savedPrefixes);
    }
    if (!is_array($savedPrefixes)) {
        $savedPrefixes = []; // If still not an array, default to an empty array
    }

    $warningPrefixes = [];

    foreach( $forbiddenPrefixes as $prefix ) {
        if( in_array( $prefix, $savedPrefixes, true ) ) {
            $warningPrefixes[] = $prefix;
        }
    }

    $permalinkOptionsUrl    = admin_url( 'edit.php?post_type=filter-set&page=filters-settings&tab=prefixes' );
    $permalinksTab          = new PermalinksTab();
    $permalinksTabLabel     = strtolower( $permalinksTab->getLabel() );

    if( ! empty( $warningPrefixes ) ){
        $message = wp_kses(
            sprintf(
                _n(
                    'Error: <strong>%s</strong> filter prefix is not allowed and must be changed on the Filter %s settings <a href="%s" target="_blank">page</a>. Otherwise this site will not work properly.',
                    'Error: following filter prefixes <strong>%s</strong> are not allowed and must be changed on the Filter %s settings <a href="%s" target="_blank">page</a>. Otherwise this site will not work properly.',
                    count($warningPrefixes),
                    'filter-everything'
                ),
                implode( ', ', $warningPrefixes ), $permalinksTabLabel, $permalinkOptionsUrl
            ),
            array(
                'strong' => array(),
                'a' => array('href' => true, 'target' => true)
            )
        );

        ?>
        <div class="notice wpc-error is-dismissible">
            <p><?php echo $message; ?></p>
        </div>
        <?php
    }
}