Author of this content has low reputation.
I find a bug with Gladuis rare cards.
So for 2nd level rare card you need five 1bcx cards to make it
but in some cases, like this
When combining 3 bcx of Alfredo it became 2/4 alfredo and it shows on the ''next lvl' graph the same thing.
I've upgraded other rare cards and i haven't had this problem.
I think it's just a visional problem.