Old debt. Some technical data and slides from RockerBox tapeout review done 10 days ago at Global Unichip.
Thanks. Could you ask them why they used TOGGLE_RATE 0.2? For SHA-256 TOGGLE_RATE should be 50%, this is pretty much a design goal for any one-way hash function.
This is part of our IP

We reduced the engine toggle rate by using innovative algorithm implemented in the Verilog. No need for custom design, we can move fast between process nodes.
It's already working in the Hammer - proven design.