When I run dnf history I get the following on line 1:
1 | | 2023-04-13 14:43 | Install | 1868 >E
This is a machine I installed in August. Is this date listed from the initial build of F38?
According to https://fedoraproject.org/wiki/Releases/38/ChangeSet Fedora Linux 38 was released on 2023-04-18.
So, this date is five days earlier than official release date.
And it was the date the iso image was build. The building process uses dnf to install packages into the images and entry 1 in the history reflects exactly was included in that install. Then the next few days is used to check if the iso file actually works.
I can see how such entry end up in the bootable installation ISO.
This is a machine I installed in August.
But how did that entry end up on the installed system?
I believe that when the system is being installed, it is done from the latest content of the repositories and the dnf history entry should list the date the packages were installed on the target system, instead of mirroring the dnf history line of the bootable ISO.
Workstation iso installs whatever is on the iso. Only the netinstall image fetches the most recent packages from the repository for install.
Ok, thanks for explanation 
I would agree with that opinion