How to make KDE 5 not blur static elements?

Question

NVIDIA

In general, from time to time I stumble upon a problem: the whole image becomes blurry. Especially where there are no moving elements (for example, a button with a view change on the "hover" event becomes clear at the time of the change, but immediately goes blurry)
. I turned them all off, but this trouble does not happen every time after turning on the computer.
Tell me, guys: how to be?
PS
KDE 5
Linux Mint Sonya 18.2
nVidia m740 GT

screens with blurring