We will be performing scheduled maintenance on October 15, 2020 at approximately 8:30 a.m. PT (15:30 UTC) to deploy the 1.12.03.00 game update. Maintenance is expected to last approximately one hour.
Important changes to MTG Arena's Maintenance Schedule:
https://forums.mtgarena.com/forums/threads/68931 This is a data only deployment, and no downtime is expected.