I don’t think this is a FOG problem. FOG is moving the files from the source computer to the target computer and the target computer boots OK. The problem you see is inside OSX itself. FOG doesn’t step inside the target OS. The only way it can do this is with the FOG Client and that is only to change the workstation name or deploy applications.
Understand the next thing I say is a guess because I don’t know. Its possible that Microsoft has connected user management or maybe password management to the T2 chip. Its possible with a different T2 chip it also protects/encrypts the password file. It may also be possible that changing the computer name does something unexpected with the user accounts. I don’t use Apple computers so I don’t have any experience with them.
From a debugging standpoint, we know that FOS Linux can access the hard drive of the Apple computer (because it can send a computer image). You may be able to use debug mode to access files on the target computer. I don’t know what you can do to reset the password externally but if you need to do things on a file level you can do this with FOS Linux. If you find a solution in debug mode then possibly you can write a FOG Post Install Script to apply those same settings during image deployment.