The crack in the shield quickly mended and vanished as if it had never existed, but Albert knew better—the shield was still there, protecting the caster.
Despite the initial surprise, Albert realized that the reality shield Golden Scale had silently cast wasn't as strong as it seemed. If it were, it wouldn't have cracked like glass when struck by an anti-mage bullet.
The anti-mage bullet nullifies mana; if it enters a mage's body, the substance within the bullet infiltrates the mage's mana pathways, rendering them incapable of using or gathering mana.
The crack indicated that the reality shield, which separated the reality in front of and behind the shield, was sustained by the caster's mana rather than by the inherent power of controlling reality itself. This meant that Golden Scale's power was still within a range that Albert could overcome without much trouble.