When moving mouse or typing, lock screen background becomes dark and blurry. This is very similar to macOS lock screen. However, the background becomes too dark. Usually people use some photos as background. If the background becomes too dark, the visual result becomes uncomfortable.
Yeah, you're not the first person to complain about it, That's why we fixed this in Plasma 5.16, where we reduced the darkening effect a lot. :)
WOW, thanks! Cannot wait to see it!
Yeah, I think you'll like it. :)
*** This bug has been marked as a duplicate of bug 398963 ***