I m also facing the similar issue.
I updated the wangGuard plugin to the latest version(1.7.0)and activated the Signup Moderation Feature. I m using the Limit Login Attempts plugin too to limit the wrong login attempts.
when I opened my login page (domain.com/wp-login.php) it had automatically attempted to login once and showed the error with the number of login attempts remaining.
Each time I refreshed the page, login attempt was made automatically. After refreshing several times my IP address was blocked for certain duration because of several automatic wrong attempts.
I deactivated the Signup Moderation feature in wangGuard and after that everything was working fine.
I wanted Signup Moderation feature on my website. Waiting for suggestions or solutions.
Thank You