The interesting thing is that the 24-core threadripper is posting a score of 20k and the 64-core one is posting 25k. Whatever Geekbench is doing doesn't appear to be something you'd normally run on one of these monster core count CPUs.
Or the overhead of co-ordinating multiple cores is starting to matter more and more the more cores you have.
They shouldn't be coordinating often unless the benchmark is poorly suited.
Only for supercomputer tasks like weather forecasting. Not for near-embarrassingly parallel jobs like high traffic web servers and render farms.
High-end Threadrippers are severely limited by their thermal envelope. Looking at the latest 5000-series products, the 64-core CPU has the same TDP (280W) as the 24-core CPU. Guess which one can sustain higher clock speeds for longer before it gets throttled.