I think Infinite's MP going F2P is a mistake and the bigger factor than Game Pass, but time will tell.
If Halo Infinite did not go F2P it would be even more dead. Remember Halo 5 had a 70% decline in NPD and sold around 5 million. F2P basically allows less popular/new MP titles to gain big userbases (people dl free games) and then try to have them spend money on MTX. Therefore the popularity of a F2P game is in its active userbase.
Halo Infinite's biggest problem now is retention. There's been a massive drop of players in 1 month.
272k -> 72k (-70%)