Rathma's Vigor's timer can't be reduced more than 2 sec for each blood orb

Rathma’s Vigor key passive says
‘This timer is reduced by 2 seconds each time Blood Orbs Heal or Overheal you for 7,959 Life.’

7,959 is the base life for Lv. 100

Anyway, even if you make ‘1 Blood orb’ heal more than 16,000 life
blood orb reduces only 2 seconds.

Is this intended? or bugged?