Rpachallenge.com website not secure

Is there any reason why the rpachallenge website is being flagged as not secure and blocked by my laptop bitdefender?

Hi,

Which protocol do you access, http or https?

As http is not encrypted, some browser/security software might show warning when we submit form etc.

In https case, as certificate of the site is not matched with its host name, browser shows warning. It’s server administrator matter.

I think we can use it via http, because there is no confidential data.

Regards,

Thanks Yoichi appreciate the feedback.

Best