Unsubscribing users via API for one specific list only

It seems that, for some unknown reason, the field list in the /unsubscribe endpoint is being ignored. We have multiple lists in our Brand and we want to use the endpoint to unsubscribe the user from a specific list from this brand. The bug is that, if the user is subscribed in multiple different lists under the same brand, even if we specify the list in the request, the user gets unsubscribed from ALL brand lists.