Will there be a minimum validity of the certificates?
On 31 May, the Commission proposed to update the Council recommendation on the coordination of the travel measures, which includes standard validity periods for tests: 72 hours for PCR tests and, where accepted by a Member State, 48 hours for rapid antigen tests.
The Regulation also introduces some basic principles, for example, setting the maximum validity period of the certificate of recovery at 180 days. These principles could be adjusted by the Commission on the basis of new scientific evidence. The Regulation in any case ensures that certificates issued by other Member States are accepted following the same rules as the ones applied to nationally issued certificates.
There is no maximum validity foreseen for vaccination certificates, as this will depend on emerging scientific evidence as to the length of protection of the different vaccines.
Sorry for late answer wasn't on here for a while.
It's literally in the Q&A section.
In spite of science proving 17 years immunity to SARS they keep it at 180 days
https://ec.europa.eu/commission/presscorner/detail/en/QANDA_21_2781