Probably an automatic precaution by itch.io, given how extensively you’ve promoted your game on other posts.
The scam warning may have its flaws, but it’s a necessary evil imo. It could save people from unknowingly downloading malware onto their PC
As for getting your game unquarantined, not much you can do about that. Just wait it out. You could try contacting itch.io support, but I doubt they’ll respond