Edge Sharpness Issue with Custom Background

I have encountered the same issue in both versions 3.01 and 3.1.

Since the Custom Background feature was introduced, it has been very useful for product rendering. However, I found one issue.

As shown in Image 1 , when the Custom Background is not used, the surface appears smooth and sharp.

However, as shown in Image 2 , when the Custom Background is enabled, the edges become noticeably blurred.

Is there any setting that can be adjusted to prevent this or improve the edge sharpness?


Additionally, I noticed a difference in rendering sharpness between versions 3.01 and 3.1.

In the attached comparison, the 3.1 render was generated at a higher resolution , yet the text on the book appears blurrier than in the 3.01 render .

Could you please check whether this is an intended change or a rendering issue?