As far as I know the primitive hidden blades in Assassin's Creed needed the removal of the finger to accommodate its use. That was what was shown in the first Assassin's Creed game - the one featuring Altair for the first time.
Then in Assassin's Creed 2 it is shown that with the specific design of Leonardo da Vinci, a hidden blade could be crafted for Ezio that would avoid dismemberment.
So chronologically Bayek is much more ancient that Altair and by that very fact the hidden blade is supposed to be much more ancient and should in fact need the removal of the ring finger for its accommodation.
But this is not the case as shown in AC Origins.
Isn't that a plot hole?