The final episode of Attack On Titan Final Season Part 2 streamed a teaser video at the end revealing that the conclusion (kanketsu-hen) of Attack On Titan Final Season will air in 2023 on NHK.

The English version of the teaser calls the conclusion as “Part 3”.

TVアニメ「進撃の巨人」The Final Season完結編
NHK総合にて2023年放送決定！
告知映像を公開しました！https://t.co/rJTn8NTtnJ#shingeki pic.twitter.com/pW0vVY7zh6

— アニメ「進撃の巨人」公式アカウント (@anime_shingeki) April 3, 2022

Attack on Titan Final Season Part 2 ended with episode 12, leaving more than 20 chapters of the manga left to be adapted in Attack on Titan Final Season Part 3.

Episode 12 included the content from the previously skipped chapter 123 of the manga titled, Island Devils. The episode focuses on a flashback where Eren, Mikasa, Armin and the other survey corps move to Marley to carry out negotiations.

The episode also featured the much anticipated scene of Eren asking Mikasa what he meant to her. The episode then shifted its attention to the Rumbling and Eren’s slow descent into accepting the bleak path that he was supposed to choose.

The Final Season’s Part 2 premiered on Jan 9, 2022 in Japan. Crunchyroll and Funimation were streaming the episodes simultaneously as they aired. The dubbed version of Attack on Titan: Final Season part 2 began airing on Toonami on Feb 12, 2022. Funimation began streaming the episodes from the next day, Feb 13, 2022.

Source: Twitter