The EU has announced that from January the Covid Vaccination Certificate will expire after 9 months.
Currently it lasts for 12 months.
This means that the Certificate must be updated with the 3rd booster jab.
Therefore many current certificates will expire at the end of December.
So everyone should get their booster and download the updated certificate.
I can confirm that my Vaccination Certificate downloaded from the App now shows my third Booster jab.
In Andalucia the only change to restrictions currently proposed is that the Covid Certificate will have to be shown to gain access to medical and health centres (although this will have to be approved by the TSJA, which is not guaranteed).
However in some regions they are requiring the certificate to access other venues.
You will probably have seen the latest regulation that UK citizens (not UK citizens resident in Spain) will from 1st December have to show a Covid Certificate showing a double vaccination.
It is not clear whether this will be subject to the EU 9 month validity, but it is reasonable to assume that this will apply from January.