Case C-324/20: Judgment of the Court (First Chamber) of 28 October 2021 (request for a preliminary ruling from the Bundesfinanzhof — Germany) — Finanzamt B v X-Beteiligungsgesellschaft mbH (Reference for a preliminary ruling — Directive 2006/112/EC — Value added tax (VAT) — Supply of services — Articles 63 — Chargeability of VAT — Articles 64(1) — Concept of ‘supplies which give rise to successive payments’ — One-time supply remunerated by means of payment in instalments — Articles 90(1) — Reduction of the taxable amount — Concept of ‘non-payment of the price’)