In Windows there's a hook on file handle close which AV products use to implement their file scanning.

I know this because I did a bunch of reading on the topic after encountering catastrophic halts inside of CloseHandle, deep inside the kernel. And even with administrator privileges I could not kill the process, or the attached debugger, and the machine was unable to shutdown because even it could not kill the stuck process. I had to hard power cycle to get back to a usable system. Near as I can tell this was because of the AV product the company was using that crashed or deadlocked or something.

Note this product was not Windows Defender.