Setup in nginx will lead to security warning in Google Chrome
Solution 1:
This warning is new in Chrome 86 and occurs when your web applicaton tries to submit a form via HTTP rather than HTTPS (or, as the bug you linked to mentions, responds to such a form submission with an HTTP redirect). Check your web application's HTML form and ensure that it posts to an HTTPS URL, not an HTTP URL, and that any redirects are to HTTPS URLs.