I sometimes face an odd phenomenon and today, again. I have a vector layer that is "blurry" without any reason.
See Screenshot below:

Of course, I carfefully looked if there's any setting wrong like "soft edge" or on the layer,"blur radiu"s and so one. Every setting is set to "none" or "plain". Settings of the eye-underline right is EXACTKY the same as of eye underline left, but, as you can see, underline right is blurry. Do you know this issue and if yes, how to fix it?