Thanks! I just had a few comments:
First, we haven't actually seen Earth-22 yet. If you want a reader to believe that Beat is this haven that's way better than Earth-22, you should show what it's like. The only scenes we have of it are Riri going down to Beat and someone sketching.
Second, you haven't really explained the world of Beat. It's underground, so is all the lighting done with neon paint? And if so, is vandalism allowed (As you described a lot of neon paint)? What are the rules of Beat? This also comes into effect with the stadium- you haven't really described what it looks like, or how the battles work.
The character's personalities also kinda confuse me. They all seem to be constantly cheerful, so they kinda blend together, making it hard to tell them apart. One good way to fix this is something JK Rowling did, where you associate your characters with key words: 'bushy brown hair'- Hermione,
'drawling', Draco', 'horn-rimmed glasses', percy. Even with minor characters, she repeated these to help you remember who everyone is. They also fluctuate- first impressions mean everything, so if Mockingjay acts edgy when we first see her, I'll expect her to keep that up.
My main complaint really is the world- you haven't really explained the rules of this place, and how it all works. What do people do all day? Does Beat have a government? If no, is it just anarchy? If the stadium doesn't allow sharp arrows, how come characters have whips shurikens and blades? A more fleshed-out world really helps the reader get a better feel for it. You can build a lot of scaffolding behind the scenes and not even show it, but it'll be noticeable that it's there. Most of my questions were about the world, including the ones I mentioned previously. Where does the prize money for the battles come from? Can literally anyone just have a go at it? If so, why don't they? Why do they partly have advanced tech and partly stuff we use today like our slang and phones?
As a last thing, we haven't had any real conflict yet. These characters are famous battlers, and I haven't really gotten a feel for their possible journeys- Reading the last chapter, I presume it's gonna start happening now, but still. What do they want? They've barely expressed opinions.
It's great overall, you have good writing for actions scenes and descriptions, but these are just a few things you could work on.
P.S.: Why is there magic? We haven't really seen characters use their powers, and the magic we've seen could be explained as advanced tech. Again, just some worldbuilding