Have you noticed that the login screen image is not clear in the new version of Windows 10. I think the Microsoft team wants users to focus on the login, not the image of “The background”.
This post provides an easy method to turn off Transparency effects in Windows 10.
Click on Start and select Settings.
In the Windows Settings window, click Personalization.
On the left side, choose Colors.
Find the “Transparency effects” on the right side of the screen and click the switch to turn it off.
To enable the “Transparency effects”, do the same process to turn off “Transparency effects” in Windows 10. When you reach the “Transparency effects” area, click the switch to turn it on.