PHP E_ERROR in APCu tab of plugin

Plugin seems to be working for me, however when clicking the fourth tab labelled APCu, I get a fatal PHP error „Es gab einen kritischen Fehler auf dieser Website.“ and a corresponding e-mail. The link is https://cyber-otter.de/wp-admin/admin.php?page=atec_wpca&nav=APCu&_wpnonce=XXXXXXXXX

• WordPress-Version 6.7.1
• Aktives Theme: Essentials (Version 3.2.14)
• Aktuelles Plugin: atec Cache APCu (Version 2.1.21)
• PHP-Version 8.3.14

Ein Fehler vom Typ E_ERROR wurde in der Zeile 651 der Datei /var/www/XXXXX/apps/cyberotterde/wp-content/plugins/atec-cache-apcu/includes/atec-tools.php verursacht. Fehlermeldung: Uncaught TypeError: preg_match(): Argument #2 ($subject) must be of type string, array given in /var/www/XXXXX/apps/cyberotterde/wp-content/plugins/atec-cache-apcu/includes/atec-tools.php:651
Stack trace:
#0 /var/www/XXXXX/apps/cyberotterde/wp-content/plugins/atec-cache-apcu/includes/atec-tools.php(651): preg_match('/#([\\-|\\w]+)\\s?...', Array, Array)
#1 /var/www/XXXXX/apps/cyberotterde/wp-content/plugins/atec-cache-apcu/includes/atec-cache-apcu-groups.php(11): atec_little_block_with_info('Persistent WP-A...', Array)
#2 /var/www/XXXXX/apps/cyberotterde/wp-content/plugins/atec-cache-apcu/includes/atec-cache-apcu-dashboard.php(65): ATEC_apcu_groups->__construct('https://cyber-o...', 'ad5e926daa', Object(ATEC_wpc_tools), 'atec_WPCA')
#3 /var/www/XXXXX/apps/cyberotterde/wp-content/plugins/atec-cache-apcu/includes/atec-cache-apcu-dashboard.php(129): ATEC_wpcu_results->__construct()
#4 /var/www/XXXXX/apps/cyberotterde/wp-content/plugins/atec-cache-apcu/includes/atec-wpca-install.php(21): require_once('/var/www/XXXXX…‘)
#5 /var/www/XXXXX/apps/cyberotterde/wp-includes/class-wp-hook.php(324): atec_wpca('')
#6 /var/www/XXXXX/apps/cyberotterde/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters('', Array)
#7 /var/www/XXXXX/apps/cyberotterde/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
#8 /var/www/XXXXX/apps/cyberotterde/wp-admin/admin.php(259): do_action('atec-systems_pa...')
#9 {main}
 thrown