6.93GB+4.70GB seems excessive though. Can understand the 4.70GB cache memory getting freed up for apps in theory although I've seen it use up nearly all 16GB RAM and not free up cache but go straight to using swap. Aside from cache, 6.93GB OS/app usage seems excessive when Windows 10 uses half and Linux less than a third.
Well, that comparison from your first Post isn't even a Fair one, because your Mac System has 16gb Ram, while the Windows and Linux machine only has 8. You Can't make a fair comparison there.
The OS will use the Ram, that's available. The Mac has 16gb to work with, so it's using that, and fills up more stuff, than it would, if it only had 8gb Ram. And this is just how it should be.
How efficient the OS is using the available Ram has NOTHING to do with how much Ram is used/free after a Boot. The difference will be visible when you push the System to the limits. I promise, a Windows Device will slow down faster than an M1 Mac would on the same Workload.
Second, don't use Task Manager on Windows, it doesn't show you the whole truth. Use Resource Monitor. That will show you your used Ram, cached ram, and free.
I have 32gb Ram right now, 13,7gb are used, 17,7gb are Cached, and 1,1gb are "free".
I'll make a Reboot right now just for the Sake of it, and edit it here. Of course, my System is not a fresh install tho.
Edit: Fresh boot, and just waiting for everything to load.
6,1gb "used", 4,1 gb "cashed", 22~ gb Free.
I am very sure, if i pulled out 3 Sticks and had only 8gb Ram left in my System, it would not have 6,1gb "used" after a Boot.
It uses what's there. If more Ram is there, there is literaly no Reason not to use it, and that's how it should be.