For two reasons: you can't format the OS partition this way and when disk is "secure erase" formatted for 4KB sector size then Windows format function doesn't offer 512b option or anything below 4KB.

I will also clarify, just in case, that when I mentioned reformatting the drive I was only referring to the second disk, not OS reinstall. I understand it could have made an impression that it was OS reinstallation that actually fixed the issue, but OS was not changed. In fact, I was able to switch the secondary drives between the computers * and the conclusion was it's about the sector size.

* - I have a desktop PC and a laptop, both with the same set of WD SN850 + WD SN570 drives, all initially formatted with 4KB sectors.

There is a fix and everything described verry well here:

https://steamcommunity.com/app/19900/discussions/0/3819658451374851852/

If you have too many CPU Cores the game won't start.
So make a shortcut in the same folder and change Target to

%ComSpec% /C Start /Normal /Affinity FFFF FarCry2.exe

also there is a 4GB patcher for DX10.