Google announced on the official Google Webmaster Twitter account that mixed content may break your pages for users and Googlebot.
If you moved to HTTPS and Chrome doesn't show a gray lock icon, there's mixed content. Mixed content is when a HTTPS page includes HTTP content, like an image or a video loading from HTTP. Upcoming changes may break the page for users & Googlebot.— Google Webmasters (@googlewmc) November 15, 2019
You’re all set if Chrome shows the gray lock icon:
The Chrome mixed content change, does it affect your site's Googlebot rendering? Probably not! If your site has moved to HTTPS and you the gray lock icon in Chrome when viewing pages, you're all set. Woot! No need to be insecure if your website is secure! #happyemoji pic.twitter.com/eHgUc5YoCQ— Google Webmasters (@googlewmc) November 15, 2019
Check your website now
Check your website with the website audit tool in SEOprofiler. The website audit tool automatically checks HTTP and HTTPS pages on your site: