Case C-596/19 P: Judgment of the Court (Grand Chamber) of 16 March 2021 — European Commission v Hungary, Republic of Poland (Appeal — Article 107(1) TFEU — State aid — Hungarian tax on turnover linked to advertisements — Information used to determine the reference system — Progressivity of tax rates — Transitional measure for the partial deductibility of losses carried forward — Existence of a selective advantage — Burden of proof)