Deprecation warnings re creation of dynamic properties

Since updating to WP 6. 7 and PHP 8.3, I am seeing a load of warnings re subscribe2

• Deprecated: Creation of dynamic property S2_Frontend::$unsubscribe is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 59
• ?Nov 13, 17:06:07Deprecated: Creation of dynamic property S2_Frontend::$subscribe is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 57
• ?Nov 13, 17:06:07Deprecated: Creation of dynamic property S2_Frontend::$deleted is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 55
• ?Nov 13, 17:06:07Deprecated: Creation of dynamic property S2_Frontend::$added is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 53
• ?Nov 13, 17:06:07Deprecated: Creation of dynamic property S2_Frontend::$no_such_email is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 51
• ?Nov 13, 17:06:07Deprecated: Creation of dynamic property S2_Frontend::$error is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 48
• ?Nov 13, 17:06:07Deprecated: Creation of dynamic property S2_Frontend::$barred_domain is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 46
• ?Nov 13, 17:06:07Deprecated: Creation of dynamic property S2_Frontend::$not_an_email is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 44
• ?Nov 13, 17:06:07Deprecated: Creation of dynamic property S2_Frontend::$not_subscribed is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 42
• ?Nov 13, 17:06:07Deprecated: Creation of dynamic property S2_Frontend::$already_subscribed is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 40
• ?Nov 13, 17:06:07Deprecated: Creation of dynamic property S2_Frontend::$confirmation_sent is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 38
• ?Nov 13, 17:06:07Deprecated: Creation of dynamic property S2_Frontend::$please_log_in is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 20
• ?Nov 13, 17:03:15Deprecated: Creation of dynamic property S2_Frontend::$s2form is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 176
• ?Nov 13, 17:03:15Deprecated: Creation of dynamic property S2_Frontend::$form is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 174
• ?Nov 13, 17:03:15Deprecated: Creation of dynamic property S2_Frontend::$input_form_action is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 116
• ?Nov 13, 17:03:15Deprecated: Creation of dynamic property S2_Frontend::$unsubscribe is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 59
• ?Nov 13, 17:03:15Deprecated: Creation of dynamic property S2_Frontend::$subscribe is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 57
• ?Nov 13, 17:03:15Deprecated: Creation of dynamic property S2_Frontend::$deleted is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 55
• ?Nov 13, 17:03:15Deprecated: Creation of dynamic property S2_Frontend::$added is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 53
• ?Nov 13, 17:03:15Deprecated: Creation of dynamic property S2_Frontend::$no_such_email is deprecated in?/home/kiivmr5gzlfz/public_html/wp-content/plugins/subscribe2/traits/ShortcodeTrait.php on line 51