UPDATE 11pm UK: Microsoft has now confirmed today's leak that Halo Infinite's multiplayer will indeed be free-to-play and run at 120FPS on Xbox Series X.
There's no word on how the mode may be monetised (an earlier report, below, suggested a battle pass model), or how this fits in to other whispers about Xbox Live Gold no longer being required to play free-to-play games one (though it would make sense).
More details will be shared later, Microsoft said, making the news official via Halo's Twitter account:
ORIGINAL STORY 10.30am UK: Leaks have suggested Halo Infinite's multiplayer will be free to play.
Details of the unannounced multiplayer were initially posted by retailer Smyths Toys, which described it as a "groundbreaking free-to-play multiplayer experience" with "greatly reduced load times" and up to 120FPS gameplay on Xbox Series X.
Xbox leaker Klobrille, who has previously detailed other Halo Infinite features before their official reveal, chimed in to say the game's multiplayer would indeed be free-to-play, and offer some kind of battle pass system.
Eurogamer has contacted Microsoft for comment.
Halo Infinite is due to launch later this year for Xbox Series X, Xbox One and on PC via both the Microsoft Store and Steam. A free-to-play multiplayer offering would open up the game to a vast playerbase - and could be especially important for the Steam audience who do not have access to Xbox Game Pass.