In addition, it is also necessary to destroy at least 30% of all buildings. The attacker must use at least a third of the maximum size of the army (including heroes, spells, and donated warriors, if any) that the defending player may have (depending on the level of his town hall).

For the destruction of less than 30% of buildings, 30 minutes of protection is required. The defense did not survive, but they did not give me the shield! As far as I understand, the enemy successfully attacked your village, but you still did not get the shield? Read the rules for providing a shield:

If you attack another village, the duration of the shield will be reduced. That is, the shield will continue to protect your village, but for a shorter time. The time by which the effect of the shield will decrease is indicated under the “Selection” button before the battle.