Different monitoring tools present the concept of "free" vs "available" memory differently, which can be highly misleading. The only one I pay any attention to anymore is free -m, please see my CPX 2024 slide deck for how to properly interpret the output of this command:
Be Your Own TAC: Advanced Gateway Troubleshooting Commands
Bottom line is ignore the "free" value and focus on the "available" value, hopefully there are separate OIDs for each of these.
Attend my online "Be your Own TAC: Part Deux" CheckMates event
March 27th with sessions for both the EMEA and Americas time zones