From GameWatcher: “Halo Infinite will not reward XP upon completing matches at launch, developer 343 Industries has confirmed. Instead, the upcoming first-person shooter will have its Battle Pass progression tied to challenges.
Community Manager John Junyszek did, however, clarify that “playing and winning matches will be challenges, which will help players progress through the Battle Pass.””
Source: N4G PC Halo Infinite Battle Pass Progression Tied to Challenges, No XP Per Completed Match At Launch