Fatal error with version 1.10.21

Hi there

The latest error has caused a complete website crash. I have disabled the plugin for now. If you could have a look at the issue please. The error is:

An error of type E_ERROR was caused in line 128 of the file /var/www/html/example_website/foo_bar/wp-content/plugins/popup-by-supsystic/modules/options/mod.php. Error message: Uncaught Error: Undefined constant "PTS_LANG_CODE" in /var/www/html/example_website/foo_bar/wp-content/plugins/popup-by-supsystic/modules/options/mod.php:128
Stack trace:
#0 /var/www/html/example_website/foo_bar/wp-content/plugins/popup-by-supsystic/modules/options/mod.php(14): optionsPps->getAll()
#1 /var/www/html/example_website/foo_bar/wp-includes/class-wp-hook.php(308): optionsPps->initAllOptValues()
#2 /var/www/html/example_website/foo_bar/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters()
#3 /var/www/html/example_website/foo_bar/wp-includes/plugin.php(517): WP_Hook->do_action()
#4 /var/www/html/example_website/foo_bar/wp-settings.php(623): do_action()
#5 /var/www/html/example_website/foo_bar/wp-config.php(98): require_once('...')
#6 /var/www/html/example_website/foo_bar/wp-load.php(50): require_once('...')
#7 /var/www/html/example_website/foo_bar/wp-login.php(12): require('...')
#8 {main}
 thrown

System information:

WordPress version 6.2.2
Active theme: Wicky Child (version 1.0)
Current plugin: Popup by Supsystic (version 1.10.21)
PHP version 8.0.5

Cheers
Chris