PHP Deprecated error

Would anyone please know what is causing this message in the debug file of my wordpress installation:

PHP Deprecated: trim(): Passing null to parameter #1 ($string) of type string is deprecated in /www/doc/www.mydomain.com/www/wp-content/plugins/better-wp-security/core/core.php on line 1102

Line 1102 of the core.php file then is

$home_path = trim( $home_path, ‘/’ );

The PHP Deprecated line keeps being added every few seconds, I have thousands of them in the debug file.

I am running PHP 8.1.18. All my plugings and WP core are the latest and up to date.

Thanks