If you want the whole background on the Database issues you can check the main thread. They discussed putting up this PTR to test some Database Architecture changes quite some time ago. They screwed up big time taking a database from 2000 that was scaled for Regional application and trying to scale it to 2021 Global use across multiple platforms. It still had the old code and some single process bottlenecks. It fell over dead, crashed the servers, lost chars, lost data, etc.
If you mod you might understand why changing the database structure and coding after Live release is an issue. In my opinion I have no idea why they did not do it BEFORE release… but yeah.