there is a way to play on steam deck, guide here
https://itch.io/blog/393053/how-to-play-itchio-games-on-the-steam-deck
But if that is a hassle or you are unable to do, you can issue a refund to itch or just tell me and I can help notify itch io
i have submitted a refund request to itch. Please check your email for the screenshoot the refund should be issued in a day or 2 or so
If you wish to also submit a refund request yourself you can do so here https://itch.io/support
i am unable to answer that when will it be back on steam question as I am also currently at the mercy of steam’s tax party but if all things goes well then maybe the fastest I can go back there is October but don’t take it a certain thing