There has not been a new Castlevania game since forever. The closest thing we have to that was the Anniversary Collection that was released back in 2019. And it looks like another collection may be on the way, according to what showed up in the Australian ratings board.
More specifically, a Castlevania Advance Collection has appeared in the Australian Classification Board. The title got listed with an M for fantasy violence for the country on 18 June. PC Gamer spotted the rating, and speculates that it will be a re-release of GameBoy Advance titles in the series. This includes the likes of Circle of the Moon, Harmony of Dissonance, and Aria of Sorrow.
Also part of the Castlevania Advance Collection rating is the multi platform label. Which is pretty vague, making it difficult to predict where it will actually show up on. It makes sense for PC, since the Anniversary Collection is on Steam. Equally possible is the Nintendo Switch, if it really is going to be a collection of GBA titles. But for the two console brands, there’s just as much reason for why the title will be available there, as it is for why it won’t.
No word on when Konami will be unveiling the Castlevania Advance Collection officially. Though now that its existence is in the news, it should be only a matter of time.