The senhasegura allows saving the data of a certificate such as key and value, in pem format, inside a secret and consuming the certificate through external secrets.
In this case, the certificate should be saved as a value, for example, in a secret:
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----