3 hops for something like an exchange, and 5 hops for something like a government (since a government has more resources) That's what is supposed to be but generally, it's the opposite. Most governments have fewer resources than companies using blockchain forensic companies.

The number of hops was something Andreas was talking about in a video long ago. I'm too lazy to look what's the exact video but it should be a video about coinjoin or mixers

As for blender.io, I was smelling something like this the last month but since the proof is only what matters and I didn't have...
It won't be the last for sure but the persons running such service should anticipate before. It's all about being pro-active