Trying to access array offset on value of type null in /includes/class-core.php

WP 5.6.1 Multisite on Linux PHP 8.0.1 emits 2 identical php warnings ONLY when Captcha settings > ‘Hide for logged in users’ is disabled (unchecked). Otherwise your plugin continues operating nice and quiet.

The two warnings are only issued each time the simplest page or post is opened in WP block editor. A test page/post only needs one new default contact form 7 ( 5.3.2) with an editor generated WC Captcha shortcode.

In the log:
PHP Warning: Trying to access array offset on value of type null in … /wc-captcha/includes/class-core.php on line 630

Line 630 was:
$session_id = Wc_Captcha()->cookie_session->session_ids[‘multi’][$this->session_number ++];

Thank you Md Rimu Chowdhury for sharing your work in creating a captcha independent of Google. Bravo. Happy hunting.