Hi @Souk Nomichith 👋
There is no official date yet. Unito mentioned that "Trello has shelved the development of its Mirror feature announced for now."
If you are looking to use two-way syncing, there are 3 Power-Ups that Trello suggests using:
Unito: With Unito you can duplicate entire cards or boards in two ways, which means that updates made to any version of a card are automatically reflected in all other duplicates.
Placker: Placker integration allows you to configure various types of syncs between boards and cards. See how to get started with Placker here.
CardSync: The CardSync integration allows you to create and manage groups of cards that are synchronized with each other on multiple boards.
Hope this helps 😃
All the best,