The chip is a qualification sample, which means the design is close to finalization.
As a general rule, higher core count chips tend to come with much lower base and boost frequencies, due to the increased thermal generation within the package. For instance, AMD's 32-core 64-thread EPYC 7601 has a 2.2 GHz base and 3.2 GHz boost frequency, which could suggest that either Rome's doubling of cores required yet more adjustments to reduce heat (even with a smaller, more efficient 7nm process), or that this is a model with a lower TDP than the flagship parts. AMD hasn't revealed the TDP ranges for its EPYC Rome processors, but the previous-gen models span from 120W to 180W.