The Download the disk image page lists always the last version of the image. This is intended, as each new version is supposed to be build on updated software (Raspbian, Moodle, etc.) and is hopefully provides enhancements 😆.
However, you can see the Version 3.5.0 page (like other "versions" pages) links directly to the correct version 3.5.0, if you want to download this exact version.
Nevertheless, I've just added an info on the download page so that users can easily find older versions.