Yes, it is mandatory for Annex V of Regulation (EU) 2019/2020 to be used as part of the conformity assessment procedure to demonstrate compliance of light sources with the requirement for functionality after endurance testing.
Disclaimer: Please note that the European Commission cannot provide a legally binding interpretation of the EU legislation, as this is the sole competence of the European Court of Justice. Any remarks from the European Commission services are without prejudice to the position the Commission might take should related cases arise in a procedure before the Court of Justice.