Explanation/Reference:
Reference: https://gdpr-info.eu/art-7-gdpr/

This is an issue that addresses two very important points - sensitive data and data from minors.
As these are, it is necessary to inform the Supervisory Authority and those responsible for the data subjects. Article 34 mentions:
1. When the personal data breach is likely to result in a high risk to the rights and freedoms of natural persons, the controller shall communicate the personal data breach to the data subject without undue delay.
Recital 38 says:
Children merit specific protection regarding their personal data, as they may be less aware of the risks, consequences and safeguards concerned and their rights in relation to the processing of personal data. Such specific protection should, in particular, apply to the use of personal data of children for the purposes of marketing or creating personality or user profiles and the collection of personal data with regard to children when using services offered directly to a child. The consent of the holder of parental responsibility should not be necessary in the context of preventive or counselling services offered directly to a child.

Verify that the processor has sufficient security guarantees that are essential for the Controller to remain in compliance with the GDPR. Remember that the responsibility is always of the controller who must take care of the data of the data subjects that have been entrusted to him.
Recital 81 mentions the following:
(81) To ensure compliance with the requirements of this Regulation in respect of the processing to be carried out by the processor on behalf of the controller, when entrusting a processor with processing activities, the controller should use only processors providing sufficient guarantees, in particular in terms of expert knowledge, reliability and resources, to implement technical and organizational measures which will meet the requirements of this Regulation, including for the security of processing. The adherence of the processor to an approved code of conduct or an approved certification mechanism may be used as an element to demonstrate compliance with the obligations of the controller.