Hey Imsopov,
Can you reproduce this in a new blank project using starter content?
If you could provide me with a comparison shot between a lower resolution reflection capture actor and the higher one, I can perhaps get the issue to appear on my end.
I tried comparing the 4.11 Realistic Rendering to the 4.12 version, and did not have any noticeable difference in the ‘shininess’ of the objects in the scene.
Thank you,