Notice: Array to string conversion in Cleantalk\Common\Firewall\Modules\SFW->_die()

Since upgrading from 9.1.5 to 9.1.8 I am seeing the following PHP errors in watchdog:

Notice: Array to string conversion in Cleantalk\Common\Firewall\Modules\SFW->_die() (line 258 of /public_html/modules/contrib/cleantalk/src/lib/Cleantalk/Common/Firewall/Modules/SFW.php) #0 /public_html/core/includes/bootstrap.inc(600): _drupal_error_handler_real(8, 'Array to string...', '/...', 258, Array)
#1 [internal function]: _drupal_error_handler(8, 'Array to string...',/...', 258, Array)
#2 /public_html/modules/contrib/cleantalk/src/lib/Cleantalk/Common/Firewall/Modules/SFW.php(258): str_replace('{SERVICE_ID}', Array, '...')
#3 /public_html/modules/contrib/cleantalk/src/lib/Cleantalk/Common/Firewall/Firewall.php(231): Cleantalk\Common\Firewall\Modules\SFW->_die(Array)
#4 /public_html/modules/contrib/cleantalk/src/EventSubscriber/BootSubscriber.php(175): Cleantalk\Common\Firewall\Firewall->run()
#5 /public_html/core/modules/ban/src/BanMiddleware.php(50): Drupal\cleantalk\EventSubscriber\BootSubscriber->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#6 /public_html/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(47): Drupal\ban\BanMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#7 /public_html/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(52): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#8 /vendor/stack/builder/src/Stack/StackedHttpKernel.php(23): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#9 /public_html/core/lib/Drupal/Core/DrupalKernel.php(708): Stack\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#10 /public_html/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request))
#11 {main} .

I had not seen these errors prior to the upgrade.