Unfortunately, Blizzard didn't launch a new Archives mission for this year's run, perhaps due to its work on the upcoming Overwatch 2. What the event does offer, though, is new mechanics and twists for its PvE brawls.
As GamesRadar notes, in one of the missions with Tracer, Mercy, Reinhardt and Torbjörn, enemies drop lava when they die and players will have half their health, as well as suffer more damage. You can only damage enemies with critical hits in another Archives mission with Moira, McCree, Reaper and Genji, and in some cases, you can only damage a player if they're nearby. Finally, the mission that launched last year with Tracer, Winston, Mercy and Genji prevents you from supporting heroes and reduces healing capabilities, among other things.
Like in previous years, you can earn new skins and emotes from the event. You can also win a Holi Symmetra, a Rustclad Torbjorn and a Bear Mei skin if you participate in the weekly challenges.