Okay, there is a 0% chance this is correct because it doesn't completely fit and I haven't even read this book (and don't particularly want to). But just because I think it's funny, I'm going to guess #248 as the infamous Magic: The Gathering tie-in novel, War of the Spark: Forsaken!
"awesome superhero comics" - the Gatewatch are basically superheroes, and they do appear in comics, though this isn't one.
"aren't just the generic buff hot white people fighting for the fate of the planet?" The stakes are higher than a "planet". Also, most of the Gatewatch are not, in M:TG color pie terms, white; that's mainly just Gideon in this era, IIRC. Chandra is red, Nissa is green, Jace is blue, etc. Okay, I guess Kaya is also in this book (ironically, she's dark-skinned, but she's white-black in color pie terms), so that's a second "white" person…
"angst and drama with a canon gay couple" - Chandra and Nissa. They may not be canon gay in THIS book, but they are elsewhere!
"a newly out bisexual's unrequited feelings for another man" - "Chandra had never been into girls. Her crushes - and she'd had her fair share - were mostly the brawny (and decidedly male) types like Gids." Probably at least one of those decidedly male crushes is unrequited, yeah? I don't think Gideon is ever actually "into" her back? Again, she's not into girls in THIS book, but she is in current canon, so it's "newly out" in terms of the real-world timeline rather than this book, since she finally got together with Nissa in like, what, 2023?
"a strong lesbian and her flirtatious 'friendship' with a girl who SWEARS she's straight" - Nissa is the strong lesbian (at least, she's a lesbian in current canon, or at any rate she likes one (1) girl). Chandra, in this book, swears she's straight; see the infamous quote above.
"toxic fuckboy MESS that is that straight girl's boyfriend" - I don't think this fits, not least because I don't think Chandra has a boyfriend in any M:TG materials? But there are many and I haven't read most of them, so who knows.
"a kid with quips… who actually has way more to him than that!" - This is Jace, who is known (and sometimes disliked) for the witty things he says on blue cards, but he's a better developed character than people seem to think. Just look at him in the Ixalan story! (Not that any of that happens in Forsaken, of course. I assume.)
"Exactly one person on this team is canonically straight," - IT'S CHANDRA. SHE IS CANONICALLY STRAIGHT IN THIS BOOK. CHANDRA HAD NEVER BEEN INTO GIRLS ETC. (I'm hoping none of the others are explicitly confirmed straight in the book, so that we don't know for SURE they're straight and it's not technically CANON…)
"and absolutely none of them are capable of being normal about the ways they handle their feelings" - Sure, probably?
See, look! Wow! It actually fits okay, except for the part where it almost certainly doesn't and I'm justifying it in the most tortured way based purely on this book's awful reputation and that one dumb quote where they tried to make Chandra and Nissa into gals being pals… But you know what, good enough. I'm satisfied with this!
