Well, episode 9 is still in development. And considering that the pattern so far has been 4 episodes per season, it's safe to say that season 3 is still a long way from even showing up on any stores.
Of course you could go straight to Patreon and get each episode as they are released individually. It will cost you more of course.

Thanks. Never touch Patreon, even though I know they can get the full game, while the rest of us waits 6 months! The Adult VN game genre, is the most awkward, sometimes disingenuous, sometimes borderline criminal, yet produce the best characters and stories of any genre. Makes it quite a quandary for me! :)

Right now on Patreon you can get the interlude for Season 3 which is a lot shorter than the single eoisodes. The interlude also serves as executable for Season 3 but as it has been said nly episode 9 eill be released next month or so and it is a loooong time until we can even talk about a complete season. Since BADIK comletely addicted me, I decided to double dip. Buy on Patreon now (GOG saves are comnpatible) and buy on GOG again when the season are finished.

Well, I have a different attitude to Adult VN's now. I just wait until I actually know for a fact in is the full story/game. Not going to invest in any Adult VN that isn't finished. I mean, only Adult VN games can say "1.0" without it meaning it's the full game! And I have seen comments for an Adult VN on Itch.io complaining bitterly about paying $5 for a 0.65 version that only had 40 mins of gameplay!!!

In that case: happy waiting ;)
As far as I know the dev is aiming for 14-20 episodes and it takes him several month to finish just one episode since he develops the game all by himself. Might take a few years until the game has been finished.

Episode 9 from Season 3 may be here before 2023.

Episode 9 was released in December. Episode 10 was approximately 40% complete at the end of February. Close to 50% at the end of March. Although they jumped to about 57% in early April. They also released an update for bug fixes for episode 9 (slowing down progress) and upgraded the graphic cards on all their machines (slowing down progress) to eliminate the rendering bottleneck (really speeding up).

Note: The author doesn't declare how much progress they make... not exactly, so the % is inferred based on the information the author does share.

In the perfect world, episode 10 is released on Patreon in July. I assume the next two episodes would also take 6-7 months each. That would put season 3 out by around September 2024ish. That may be optimistic, but it's a rough guess on when to start checking in if you don't want to follow the author. They work alone so any sickness or emergencies and production halts.