https://www.epo.org/en/service-support/faq/applying-patent/validation-system/are-validated-european-patents-governed

Are validated European patents governed by the European Patent Convention (EPC)?

For all European patents, including validated patents, the EPO conducts the search and examination in accordance with the EPC. However, once granted and validated, the patent has the same legal effect as a national patent in the validation state. Therefore, the national law of the validation state applies to the validated patent, not the EPC.