Right.

Another day, another mail from Google:

To owner of http://zeigermann.com,

Starting October 2017, Chrome (version 62) will show a ‘NOT SECURE’ warning when users enter text in a form on an HTTP page, and for all HTTP pages in Incognito mode.

The following URLs on your site include text input fields (such as < input type=”text” > or < input type=”email” >) that will trigger the new Chrome warning. Review these examples to see where these warnings will appear, so that you can take action to help protect users’ data. This list is not exhaustive.

Here’s how to fix this problem:

Migrate to HTTPS
To prevent the “Not Secure” notification from appearing when Chrome users visit your site, only collect user input data on pages served using HTTPS.

Well, I’ve now converted the whole domain to https. Hope this works.