Ah, this feels like the ending of Demon Slayer, albeit a little different. The ending arcs of Demon Slayer and Beastars are similar in the sense that they ended with defeating the big baddie in a long, drawn-out battle. I guess the difference is that Muzan was known about pretty early while Melon was pretty fresh, which I feel complicated some things about the story since I feel like Paru wasn't 100% sure what to do with him. I also kinda feel these arcs suffered for different reasons.
For Demon Slayer, it suffered because it was too long + how the chapters explaining what happened after the big baddie was defeated weren't really enough. For Beastars, the arc + the ending suffered from a combination of things that happened before and during the last arc. Again, it felt like things with Melon weren't planned for, and I also think the battles within the arc lasted way longer than Demon Slayer's since Paru fit in all of these mini-battles with the different groups in the back alley market. With the mini-battles, I feel like Paru was trying to fit in some narratives about each of the groups (the one about the inarigumi is the one I can remember most clearly), however that is a lot of info to fit into a sub-battle, so I think people end up forgetting information like that.
There's probably more I could list, but those are the things I can remember. It's a shame to see this story get axed, but here's to hoping for more stories from Beast Complex! Pretty excited to read some more stories about the world Legoshi and friends live in, especially after all of the important things that have happened in this one.