Caused by the wrong setting. According to the detailed information of cool music rendering, it is known that a whiteboard that cannot be deleted is caused by a wrong setting. The solution is as follows:

1. Open the picture to be rendered, and you can see that it is much noisier than the previous version.

2. Select "V-ray"-"Global Switch" in the toolbar on the right, and you can see that the default setting of probability light is 83.