Isn’t this all about viewership/loyalty?
If I were DnA, I’d be upset too. They’re providing the readers with free content that they’ve spent hours on. It’s disrespectful to disregard their efforts. It was also disrespectful to swoop in and translate later chapters without doing translations starting at chapter 1. It’s the intention that is questionable. It just comes off as stealing an already established readership that was gained through DnA efforts and not your own. In my opinion, that’s the problem.
Yes, it is unethical to translate the author’s work without their consent. Furthermore, as this is a career for the author. It’s how they’re funding themselves. It’s basically robbing them of income & stealing their work. But the original translating group shouldn’t be under-minded to this degree for instant gratification. It’s okay to see both sides of the coin. It’s okay to say you prefer the new translation group. But don’t just basically tell the previous translation group to get over themselves when they were the ones who started translating this on this platform.