This warning comes from the Boehm Garbage Collector, an open source GC used by the Mu language.
If you have custom Mu code in your workflow, you might want to look for large allocations. I am not 100% sure this warning means that there are leaks, by looking at the GC code, this seems to detect when there are multiple large memory allocations (>5 by default and we’re not changing it in RV).