You should establish when the goods are physically located. If they physically move between the UK and the EU, they are treated as export/import. If they physically move between Northern Ireland and the EU, they are treated as intra-community movements. In such case Intrastat and EC sales are required as before.
From the 1st of January, Intrastat and EC sales lists are not required for movements between the UK and the EU. However, Intrastat is still required for imports from the EU until 31st of December 2021.