Ok so yeah first off. The grind is real and while I love challenges, they are for now the only way to progress. Its NOT fun, meagetly worth it. For sloooowly battering through the season pass and weekly, ultimate challenges so on so forth.
Yes yes I bet you have economic analysts trying to balance the line while looking for ways to squeeze money out of folks. Yes, you at 343 need a living and MS their share. So I kinda understand tve pricing bu STILL
Anyway here are my recommendations, might need some refinment but at the core it is as it stand. Grab some drinks and read on whoever you are
SO!
1: Earning XP with challenges is fine but dosent reward player performance and progression.
2: Besides challenges. Players should earn XP / Credits through kills, assists, objective score
3: Same as point 2 but also through Medals. The more difficult the medal is to do, accomplish, the more XP/ Credits should be rewarded.
4: I included / Credits in above points. The progression needs it so there are other ways to get CR that to spend HARD earned cash, there are people old and young struggling with getting easly tempted by pay to progress, let them avoid that by havin them and others, like myself get CR by just playing as well.
An amount thats enough worth the accomplishment of a won match, hard to do performance medals etc. BUT yes, not undermining the option and your income as a studio either. Understandably, you need earnings too.
DONT make the free to play model not even near predatory, dont do the same vile thing as other " free to play " Because it will be expensive yo play for those who cant help themself.
5: You could mix and match XP/ CR rewards to be fair and satisfying by playing. Be it for the Challenges themself, wins, performance based medals etc Also completing weekly, ultimate or even the season itself could net a chunk of Credits. If not in addition to a visor color then for example 500-1000 Cr could be generous.
But the visor color or whatever could be earned/ bought elsewhere. Another example. If visor color + Cr, have it be like 250 cr with the visor color
Regarding meda rewards example:
Double kill = 25 xp + 15 Cr each, 50 xp and no Cr
Overkill = 75 xp + 45 Cr each, 150 xp and no Cr
Demon and Invincible should REALLY net hefty rewards like in thousand range. 1000 XP, 500 Cr. Along those lines.
Holding Oddball, capturing flags, keeping territories, getting fuel cells should also be rewarded similarily.
6: Now punishment for quitting, teamkilling more than one should NOT reward anything. Its need to be big prejudice against such behaviour.
Have the game kinda watch over a player that teamkills once, if another teamkill occur in a short duration after. There should be minimum to zero gain of xp/ cr. Preferrably NO Cr at all!
One teamkill should take away 10 - 25 % of final scores " earned " xp and or credits.
Teamkilling AND qutting thereafter should absolutely not give anything, zeto, nada
7: Otherwise. Love Halo Infinites multiplayer, thanks! Now fine tune the progression system, even look to a pretty little game called Deep Rock Galactic for inspiration. In their first attempt at a seasonal battle pass, they have not only made a 100 tier linear progress bar but ALSO a branching cosmetic tree to use earned scrip points which are again earned through gameplay, on. While they have for now 4 classes of dwarfs. YOU, 343 have several lines of cosmetics as well.
You could have something similar. Room for additional earnable/ unlockable stuff but a bit quicker than the BP progression tier line but at the cost of more demanding challenges etc.
Different separate branches with only armors, helmets, kits, poses, coatings, decals & other smaller things like charms and so on.
So thats that, my suggestions. Lots of room for improvement. Hope I inspired, take care and stay safe 