The answer to this question is provided by the European Commission.

The Notice regarding the adaptation in line with inflation of the amounts laid down in the Directive 2009/138/EC of the European Parliament and of the Council on the taking-up and pursuit of the business of Insurance and Reinsurance (Solvency II) (2021/C 423/12), published on 19 October 2021, states: “The revised amounts shall be implemented by Member States by 19 October 2022.” This means the revised amounts will come into force as of 19 October 2022. Replying to the question of whether the first calculation using revised amounts should take place in the fourth quarter of 2022 or in the first quarter of 2023, the first calculation of the MCR taking into account the revised amounts should take place in 2022. Therefore, the updated floors indicated in the Notice should be the reference for calculations of the MCR for Q4 2022 and YE 2022 and, if pertinent, for any other calculation of the MCR between 19 October and YE of 2022.

Disclaimer provided by the European Commission:
The answers clarify provisions already contained in the applicable legislation. They do not extend in any way the rights and obligations deriving from such legislation nor do they introduce any additional requirements for the concerned operators and competent authorities. The answers are merely intended to assist natural or legal persons, including competent authorities and Union institutions and bodies, in clarifying the application or implementation of the relevant legal provisions. Only the Court of Justice of the European Union is competent to authoritatively interpret Union law. The views expressed in the internal Commission Decision cannot prejudge the position that the European Commission might take before the Union and national courts.