I was wondering if your tool was displaying cache as usage, but I guess not. Not sure what you have running that’s consuming that much.
I mentioned this in another comment, but I’m currently running a simulation of a whole proxmox cluster with nodes, storage servers, switches and even a windows client machine active. I’m running that all on gnome with Firefox and discord open and this is my usage
$ free -h
total used free shared buff/cache available
Mem: 46Gi 16Gi 9.1Gi 168Mi 22Gi 30Gi
Swap: 3.8Gi 0B 3.8Gi
Of course discord is inside Firefox, so that helps, but still…