Attack on Titan Final Season is receiving a Part 2 that is expected to release in 2022. The hit anime series is currently airing season 4 in Japan as well as internationally via streaming services like Crunchyroll and Funimation. In the U.S., the English-dubbed release of Attack on Titan Final Season has also been airing on Adult Swim's late night Toonami programming block, though delayed by a few weeks. As its name suggests, this is to be the final season of Attack on Titan, but this final season is being extended.
As readers of the Attack on Titan manga on which the anime is based already know, there is more story left to cover than what the remaining episodes of season 4 would allow. Knowing this, many had already guessed Attack on Titan Final Season would be continued in some fashion, with an announcement of a movie to wrap everything up considered a likely option. However, the studio responsible for Attack on Titan Final Season, MAPPA, has instead announced a second half to the final season.
Attack on Titan Final Season episode 16 has only just aired in Japan, and though initially billed as season 4's final episode, it was accompanied by a teaser for episode 17 (via @AnimeTV_JP). Attack on Titan Final Season Part 2 is announced as returning "this winter", which likely means early in 2022.
While admittedly vague, anime release schedules typically follow a quarterly pattern and Winter shows generally release in January or February. This makes it likely that a release "this winter" means early in 2022. However, Attack on Titan Final Season Part 1 began airing in late December, so a release in the final weeks of 2021 isn't entirely out of the question.
As of the most recent entry in the anime, season 4 episode 16 "Above and Below", the show has 23 chapters of the manga left to adapt. Previously, Attack on Titan Final Season Part 1 adapted 26 chapters of the manga in its 16 episodes, so it tracks that the remaining chapters of the manga would be enough to fill at least another 16 episodes. With so much story still left to cover, the decision to add a second half to Attack on Titan Final Season is a much better choice than a movie. While a film could potentially be a more high profile way to finish off the popular series, a batch of new episodes will allow Attack on Titan the screen time necessary to give the story's ending the attention it deserves.
Source: MAPPA via @AnimeTV_JP