PMM Monitoring Mongo Remotely Using Too Much Memory

PMM version: 2.23.0

I have 10 EC2 Mongo that I added to PMM. I am not using the pmm-agent so I added the Mongo through the UI itself following this: Percona Monitoring and Management

Note that before this memory spike, PMM has been monitoring ~50 Amazon RDS instances and memory usage has been constant.

After this, I started seeing the memory of PMM slowly climbing up. See below.

If I remove the 10 Mongo being monitored, PMM will go back to the regular memory usage. So, is this expected that if I add Mongo remotely without using a pmm-agent, it will use this much memory or more?