Judgment of the Court (Fourth Chamber) of 15 June 2023.#Arkadiusz Szcześniak v Bank M. SA.#Request for a preliminary ruling from the Sąd Rejonowy dla Warszawy - Śródmieścia w Warszawie.#Reference for a preliminary ruling – Unfair terms in consumer contracts – Directive 93/13/EEC – Article 6(1) and Article 7(1) – Mortgage loan indexed to a foreign currency – Conversion clauses – Determination of the exchange rate between that foreign currency and the national currency – Effects of a finding that a clause is unfair – Effects of the annulment of a contract in its entirety – Possibility of asserting claims that go beyond the reimbursement of the amounts agreed in the contract and the payment of default interest – Damage incurred by the consumer – Unavailability of the amount of the monthly instalments paid to the bank – Damage incurred by the bank – Unavailability of the amount of the capital paid to the consumer – Deterrent effect of the prohibition on unfair terms – Effective protection of the consumer – Judicial interpretation of national legislation.#Case C-520/21.