How to exit from full screen mode on Standalone? 3d content stretching.

After I’ve updated the Unity to 2018.3.11f1 from 2018.3.6f1 I have a problem. When I press full screen button 137408-1.png

I can’t see the panel with it anymore. I’ve tried to play with PlayerSettings: Resolutions and presentations but nothing helped.

Why do I need it? Because after scene load I have screen “scaling”:

Rings look stretched, but they shouldn’t be. To fix it before I had to press twice on that “FullScreen” button I’ve shown above. This is 3d rings, UI works well.

Any ideas?

Fixed in 2019.1