Announced early this morning, the Core 2021 set debut stream that was planned for today has been postponed. Additionally, the banned and restricted updates that were announced earlier this week are also postponed.

Quote From @wizards_magic

We'll be postponing the debut of Core Set 2021 until Friday at 7 a.m. PT out of respect for the National Day of Mourning. #MTGM21

This includes the previously scheduled game update and implementation of the June 1 banned and restricted announcement. We will have updated maintenance times as soon as possible. (@MTG_Arena)