Cache hit ratio deteriorating over time with CLFUS

We've observed poor cache hit ratio with the CLFUS, where it starts doing great, but over ~1 day, the cache hit ratio deteriorates. It's to the point where the LRU + seen-filter=1 is 2-3x better. In addition, the RAM cache hit ratio on the LRU stays consistent over time.

At first, I thought it was only our particular use case, but it seems others have confirmed the same behavior.