I think the first time I knew who was developing the BR mode, known as Firestorm by the way, was with the official announcement in a blog post.
FIRESTORM: FIRST DETAILS OF BATTLEFIELD V'S BATTLE ROYALE MODE
Go to the link to read more information about Firestorm.
Thanks. I must be thinking of another game then or it may just be from before the official announcement since I never kept up with BR modes in all the coming games.