In previous versions (e.g., 23H2), EnableFastFirstSignIn would create candidate accounts like defaultuser000001. Is it missing now?
The appearance of a WsiAccount could indicate that there are underlying changes in how Windows manages accounts during Autopilot scenarios in 24H2, even if Web Sign-In is not explicitly configured.
Before proceeding the following create a System Restore Point.
In Start Search type Regedit and hit the Enter key.
Now navigate to:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Authentication\Logonui
Right-click in the right pane, select "New" > "DWORD (32-bit) Value" and name it "EnableFastFirstSignIn"
Double-click "EnableFastFirstSignIn" and set the "Value data" to "1".
Reboot.