How to find the cause of memory discepency between what the OS sees and what observer shows


I am seeing constantly and slowly growing memory usage on my production app that is deployed to

In the vm when I run top I can see that the size of the beam.smp process uses this memory.

I checked in the phoenix dashboard and with :observer the memory use and in those I only see ~350mb.

(the images are not from the same time, but they match up)

Any idea how can I find what is using this memory?

Thank you