Case C-241/20: Judgment of the Court of 15 July 2021 (request for a preliminary ruling from the Tribunal de première instance du Luxembourg — Belgium) — BJ v Belgian State (Reference for a preliminary ruling — Freedom of movement for workers — Free movement of capital — Income tax — Legislation for the avoidance of double taxation — Income received in a Member State other than that of residence — Method of calculating the exemption in the Member State of residence — Loss of part of the benefit of certain tax advantages)