The next server update has been scheduled for the 2023-01-20 somewhere between 22.00-01.00 UTC/GMT.
It will be a minor patch, so the downtime itself shouldn't be long.
What is planned:
Update Server to version v1.12.8 and api to v2.21.0
This together should hopefully fix achievements
More details found here https://github.com/FAForever/server/releases/tag/v1.12.8