Oh, that is weird. I will look into this and let you know as soon as I know what's going on. Sorry for the inconvenience!
EDIT: I can't see anything wrong on my end so I have sent an email to itch.io support to see if they can fix this. If this is urgent for you, please send me an email to email@example.com and I will give you the Steam key directly.
EDIT 2: itch.io support has told me to tell you to look again. Apparently the fraud detection system can take a while. Hope it's fixed now!