Non - conformance

First is important to note that the concept of major and minor non-conformities is not commonly used in internal audits because the type of the identified non-conformity normally does not affect the development of the internal audit (as it occurs in certification and surveillance audits). Considering that:

Minor nonconformity - a non-conformity that does not affect the capability of the management system to achieve the intended results. An example might be that you find some people have not undertaken training that the organization has made mandatory (ISO 27001 clause 7.2), but you find that those people are still competent to carry out their tasks.

Major nonconformity - a non-conformity that affects the capability of the management system to achieve the intended results or in other words, when you have found that the requirement of the standard has not been met. For example, if an organization completely failed to fulfill a certain requirement; if a process has completely fallen apart; or if you have several minor nonconformities that are related to the same process, or to the same element of your management system.

Regarding your scenario, since you have several cases in the same process, you could consider it a major non-conformity, because of its recurrence.

This article will provide you a further explanation about major and minor nonconformities:

• Major vs. minor nonconformities in the certification audit - https://advisera.com/27001academy/blog/2014/06/02/major-vs-minor-nonconformities-in-the-certification-audit/