OPNSense not able to re-claim memory space after killing multiple process

[Afif]

Are you using file system defaults (ZFS, compression)? The compression works very well on log files. (To check, "df -hT" and if ZFS, "zpool get feature@lz4_compress,feature@zstd_compress".)

I'm not using ZFS on this system. Here is the output from the command.

root@OPNsense:/home/afif # df -hT
Filesystem  Type      Size    Used  Avail Capacity  Mounted on
/dev/da0p2  ufs        29G    6.4G    20G    24%    /
devfs      devfs      1.0K      0B    1.0K    0%    /dev
/dev/da0p1  msdosfs    256M    1.3M    255M    0%    /boot/efi
root@OPNsense:/home/afif #