Docs: REPL optimization does not work with write behind

https://infinispan.zulipchat.com/#narrow/stream/118645-infinispan/subject/PriorityMergingProcessor.20used.20when.20cache.20mode.20is.20REPL_SYNC

it states in the documentation: “Currently if you are using a replicated cache the iterator or spliterator terminal operations will not perform any of the operations remotely and will instead perform everything on the local node. This is for performance as doing a remote iteration process is very costly.” but if we use f.ex. filter (kotlin) on the cache the iterator does remote calls. why is that?