Kagami gets more hate because of the narrative. She's portrayed as a rival and a "frienemy" to Marinette (and the writing goes out of its way to ensure it- I still really don't like the way she paraded Adrien like a trophy in Animaestro), while Luka is always the Nice Guy™ who never gets jealous. It's an issue with the writing as a whole. It's sexist. Adrien has a posse of girls being mean to each other because of him while Mari just gets the nice cute guys (adrien, luka, even nath). So yeaaaah.
Yeah, I get that and the issues with the narrative are a whole other text post that I will probably get salty enough to write one day.
Kagami got spunk, yes she’s been portrayed as a rival, but that is how Mari sees her so that’s how it’s portrayed to us. Maybe this is going to go off topic here but imma get it off my chest anyway because you just got me started :P
Marinette and Adrien are very very similar in how they react to their love interests. We only see it more with Marinette and her crush on Adrien because Adrien has Chloe and Kagami as other potentials, whereas Ladybug doesn’t really have the time for romantic rivals. But think back to CopyCat, Adrien gets just as jealous over Ladybug as Marinette reacts to Adrien.
In Animaestro, I didn’t really see it the same way you did - I didn’t have an issue with Adrien and Kagami hanging out or doing anything - I saw it more as “Oh our parents know each other and we are about the same age so we kinda have to entertain each other” but made easy by the fact that they already know each other and are friends. Kagami is someone who knows what she wants, she’s given Marinette the opportunity to step up and has no reason to back down. If Adrien eventually chooses someone else, then she would definitely accept that. She’s just got a more blunt personality which is why everyone just screams “bitch” whenever she’s on the screen which is just unfair to her.
Chloe is just mean, we know and love Chloe for all her flaws and Marinette is very easily led when it comes to Adrien. Plus they were frenemies before Adrien even came into the picture.
Imo (writing aside) Marinette has decided for herself that Kagami is a rival which is why it ends up like that. Kagami doesn’t deserve fandom hate for all that sort of thing, she’s done nothing wrong. She’s literally only done what Luka has done, just without the flowery metaphors but like you said - Luka’s the nice guy.
It’s almost frustrating that Luka isn’t set up as a rival for Marinette in the same way Kagami is for Adrien. Because if Luka ever started having a little thing for Ladybug, Adrien would be so pissed off and jealous, exactly how Marinette is acting now and it would honestly be interesting to see how some of the fandom’s reaction changed.
