What is the controversy surrounding Serum Institute's Covishield and EMA?

The vaccine did not make it to the European regulator's approved list, although it has been approved by WHO and also the UK MHRA

A controversy erupted around June when the European Union came up with what is called a ‘Green Pass’ that aims to facilitate free movement between the EU member nations during the Covid-19 pandemic. The AstraZeneca-Oxford vaccine manufactured by India’s Serum Institute of India (SII) did not make it to the list of vaccines that were considered as acceptable by the European regulator.

Background:

The innovator vaccine Vaxzevria as it is called, however, was recognised by the EU while Covishield, which does not have an emergency-use authorization (EUA) by the European Medicine Agency (EMA) was not recognised.

It is interesting to note that Covishield