The original pre-pandemic Marvel timeline was set up to introduce certain characters from The Falcon and the Winter Soldier in the Black Widow film, which would have been released first. Unfortunately, due to the COVID-19 pandemic, many films and television shows were delayed or stopped entirely.
As a result, the current Marvel release timeline deviates a lot from their initial pre-coronavirus plan, with a few exceptions. Phase 4 of the MCU was supposed to kick off with Black Widow, followed by Eternals, then The Falcon and the Winter Soldier. WandaVision was supposed to follow The Falcon and the Winter Soldier, which is the exact opposite of what happened in 2021!
The timeline currently in place started with WandaVision, then The Falcon and the Winter Soldier, followed by the Black Widow movie, which will release in July. The next series in the new timeline order is Loki, which arrives to Disney Plus on June 11, 2021. Initially, Loki was set for release in May 2021, but was moved back by a month — it was supposed to follow Doctor Strange and the Multiverse of Madness.
Hopefully, despite the new Marvel Phase 4 order, none of the plot points of films will be spoiled! Shang-Chi and the Legend of the Ten Rings will release in September 2021, and the Eternals will follow in November 2021, much further down the line than it was initially set to release. Fans are holding out for a The Falcon and the Winter Soldier Season 2, but nothing has been officially announced yet.