Chrome is going to block unencrypted downloads in the near future. In particular, downloads that are offered on sites that are SSL encrypted, the so-called mixed content downloads.
From Chrome 82, which appears in June, users will see alerts. From Chrome 83, the browser will completely block downloads from over HTTP connections.
In the first instance it concerns the desktop versions, the mobile versions of Chrome will follow at a later stage.
So if you are running PPI offers or have other kinds of downloads on your website: check your links and make sure they are served over HTTPS.