The Mana Reservation Efficiency mastery has been replaced as there is now a much larger amount of Mana Reservation Efficiency for Curse Auras on the passive tree." (The mastery was 30%) :
Path of Exile 3.13] How To Craft My Shield - 15% Reduced Mana Reservation & 10% Aura Effect - 713 - YouTube
Reservation - Path of Exile Wiki
Reservation - Path of Exile Wiki
Defenses and Defensive Layering in Path of Exile - POE Maxroll.gg
Gameplay Help and Discussion - Amulet with Pride has #% reduced mana reservation - Forum - Path of Exile
Bug Reports - Corrupted jewel mana reservation does nothing - Forum - Path of Exile