It doesn't natively : the main UI is rendered on another layer/camera, it's impossible to overlap with world objects.
Even with post process, the UI is "living" on another plane as the world, here I'm litterally crossing the shoulder of a character without having any of the effect you have :
View attachment 561426
So, you obviously have a plugin installed/you are using in the scene, changing the way the UI is rendered (or the objects).