As other commentators have pointed out, much like the actual Great Wall of China, the Great Firewall of China is not a singular entity but rather a patchwork of potentially overlapping walls whose policies vary by ISP, city, and province.

Inner Mongolia has been having uprisings recently, it does not surprise me that reddit would be blocked there (actually, I believe most internet was severed from Inner Mongolia a month or two ago).

Never seen it blocked here in Shenzhen, maybe a bug with the software or different location in China...