Hidden languages

Hello. I assumed that hidden languages were only visible in Admin, not in storefront.

But if I make any of my installed languages hidden, it is no longer visible in storefront, but also for the administrator : the language is no longer available in top right corner dropdown list to change the admin language and no longer visible in the dropdown list in administration/languages for translations.

Consequently, hidden and disabled have the same effect…

Is it a problem with my installation or understanding the feature ?

I've just updated to 4.0.2. Hidden languages are invisible in storefront but visible in Admin. Resolved.