【Google Compute Engine】同じマシンインスタンス（e2-micro)でもOSにより使えるRAMサイズが異なる件

Ubuntu 20.04 -> RAM=1GB

$ free
              total        used        free      shared  buff/cache   available
Mem:         976928      194180      264992         948      517756      630508
Swap:             0           0           0

Rocky Linux 8 -> RAM=0.7GB

$ free
              total        used        free      shared  buff/cache   available
Mem:         773508      284048      167452        5212      322008      368184
Swap:             0           0           0

CentOS7 -> RAM=1GB

$ free
              total        used        free      shared  buff/cache   available
Mem:        1011100      182636      646636        6708      181828      685676
Swap:             0           0           0

Ubuntu 22.04 -> RAM=1GB

$ free
               total        used        free      shared  buff/cache   available
Mem:          972472      222320      313928         952      436224      597748
Swap:              0           0           0

CentOS8 Stream -> RAM=0.7GB

$ free
              total        used        free      shared  buff/cache   available
Mem:         785772      285224      175096        5288      325452      377388
Swap:             0           0           0