Hello !
Is this normal that the site is very well available through Https, but the protocol is not enforced yet ?
For example, when you go to the addons main page with https : https://www.esoui.com/addons.php and click on the "action bar mods" category, you are redirected to http://www.esoui.com/downloads/cat19.html, but the https page is well available https://www.esoui.com/downloads/cat19.html

Maybe you can use the Strict-Transport-Security header ?

Thanks for reading :)