The Switch is technically a "generation" behind the other two, but because its selling so well and came out later in the gen than them anyway they aren't in some rush to push out the Gen 9. Especially given PS4 is still getting games made for it because no one cares or wants a PS5.

Also the new Pokemon is in a weird place where its probably one of the best games they ever made, but its performance is so bad its painful. So surface level reviews will spend all their time talking about that, whereas people who'd play it anyway get more conflicted. However, that's entirely a Gamefreak problem as games like Xenoblade 3 came out this same year with zero of those performance issues, still having a massive open world and having full voice acting on top of it.