Mirabel Madrigal explicitly blames her grandmother, Alma Madrigal (Abuela Alma), for damaging the family's miracle.
The weakening of the family's extraordinary gifts and the cracking of their magical home, Casita, culminates in a highly emotional confrontation between Mirabel and Abuela Alma. Initially, Alma blames Mirabel for the family's misfortunes, which deeply hurts Mirabel. However, Mirabel's hurt quickly turns into anger, and she retaliates by placing the blame squarely on Alma.
Mirabel's conviction stems from her belief that Alma's actions and priorities are the true cause of the Miracle's decline. She vehemently asserts that she, her estranged uncle Bruno, and all the other family members genuinely love and care for the family and its magic. Mirabel insists that Alma is the exception, implying that her grandmother's strict focus on maintaining the family's image and power, rather than fostering love, understanding, and acceptance within the family, is what truly undermines their magical foundation. This heated exchange underscores Mirabel's deep-seated belief that Alma's rigid approach and perceived lack of unconditional love are the factors destroying their cherished Miracle.