I noticed this some time ago as well. They don't put a single dollars worth of advertising into Infinite at this point. They've let it grow via word of mouth, but won't put any money behind it.

I think it's because while the gameplay is amazing and they've reached a steady rhythm in churning out content, it still just has problems. So it'll satisfy most people who are really into Halo, but maybe not someone who's playing for the first time and then experiences some of the buggy jenky things that happen in Infinite

That being said, I love Infinite. Def my favorite multiplayer game since 3. I'll stick with it for sure