When will mimalloc release the memory

I'm using the v1.7.6, have overridden the malloc/free and new/delete, I've run the Stress test for a day, and my application consumed about 9.7G memory, then I stopped the test, after 24 hours, I see the application still holds that memory but not release it, does this normal?

The report names mimalloc v1.7.6 and a long-running Stress test, but no files or tests. Start by reproducing the memory-retention behavior after stopping the test and inspect how the allocator handles unused memory. Done means establishing whether the behavior is expected or identifying a reproducible defect and its affected entry point.

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