PHP Deprecated error

I’m using v3.4.9 of the plugin and am getting a PHP Deprecation error on my local dev site where WP_DEBUG is enabled:

PHP Deprecated: Creation of dynamic property Haet_Sender_Plugin_GravityForms::$activate_plugins is deprecated in /app/public/wp-content/plugins/wp-html-mail/includes/class-haet-sender-plugin.php on line 176

I’m running PHP 8.4.10 and using the plugin in conjunction with Gravity Forms.

Thanks for all your work and support.