Thank you for posting in Microsoft Q&A forum.
The log file that contains information about files blocked by Windows Defender is the Microsoft Defender Antimalware Protection Logs.
You can find this log file in the folder C:\ProgramData\Microsoft\Windows Defender\Support. The log file name is MPLog.txt.
If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Add comment".