If I understand correctly, your contract manufacturer is in Germany. All manufacturers of medical devices that want to be placed on the EU market (regardless of whether they are sold only in the home country or also in other EU countries) must be in compliance with MDR since May 2021.
If its medical devices are already certified according to the MDD and MDD certificate is valid for example until October 2023, this MDD certificate is still valid until October 2023. This means that the contract manufacturer must prepare technical documentation according to Annex II and Annex III to be in compliance with MDR until October 2023.
In the meantime, audits that will be conducted in 2021 and 2022 will require from contract manufacturer to prepare the following documents in compliance with MDR (Article 120):
Post-market surveillance system
Mutual obligations with economic operators
For more information, see:
EU MDR Article 120 - Transitional provisions https://advisera.com/13485academy/mdr/transitional-provisions/
EU MDR Annex 2 – Technical documentation https://advisera.com/13485academy/mdr/technical-documentation/
EU MDR Annex 3 – Technical documentation for post-market surveillance https://advisera.com/13485academy/mdr/technical-documentation-on-post-market-surveillance/