Per IGN, the season 2 premier date for the Halo TV series on Paramount Plus was inadvertently leaked on the studio’s YouTube channel in the description of a season 1 video. The leak was seen by X user Mr_Rebs_, who posted a screen capture of the description prior to it being removed by Paramount. Expect it to be made official soon.
Speaking of season 1, if you need a refresher before the new season comes out, all episodes are now streaming for free on YouTube. Start with episode 1 here:
https://youtu.be/ELdWy6VIfsY?feature=shared