Language cookie is not updated with the Default Language set in XWiki Preferences

When setting up let's say a french language XWiki, I go to the XWiki Preferences and set

MutilLingual : Yes
Languages : fr
Default Language : fr

• clear cookies
• access your wiki
• click to login
• when redirected to the login page, the language is automatically set to en in the cookie
• login
• language is still en in the language cookie
• Main.WebHome has translations for french, but the cookie is still set automatically to en

To set the cookie to fr, I have to click on the default button or appent "?language=fr" in order to change my cookie language to fr.

Reported this as a bug because it is very confusing for the end user, which is expecting for the wiki to be in french even before the login page, or without having to press any additional buttons.