I don't think it's a bug, although it's possible. I've seen several similar reports, and I'm more inclined to think it's a new form of attack on Itch.
A few weeks ago, there were quite a few DDoS and bot attacks, which is why Itch had to implement much stricter security measures. If you read the forum, you'll see that these measures are affecting several users.
Personally, I'm inclined to think that the attacker or attackers behind those attacks found another way to try to overwhelm Itch's servers, bypassing Cloudfire's defenses.
To be clear, this is just my personal theory.