How does Google handle pages with mixed content
Recently, Google representative John Mueller said how the search engine handles a new HTTPS page with mixed content. As you know, this problem frequently occurs after the translation of the website into a secure Protocol.
According to the specialist, if the browser shows an alert about the presence of mixed content on the page, Google is less likely to choose this URL as the canonical.
Thus, if the page has two versions – HTTP and HTTPS, and contains unprotected content (images, CSS, Javascript, etc.), then Google will give preference to the HTTP version.
While Muller noted that this situation does not lead to sanctions and does not affect the position in the search.
He also answered a question about HTTP redirect to HTTPS version and how it may affect the choice of Google.
"It is possible that in this situation, we can choose the HTTP version [for display in the search results]. We use a number of factors in the process of canonization. While redirects are important. However, if we see clear signs that should be indexed, HTTP-version, we will choose it."