How to make background blur in unity for mobile game?

Question

Shaders

What is the point: there is an active canvas and behind it there can be an element of the world and another canvas. How to make everything behind this canvas blurry. I rummaged through a bunch of information and looked at different shaders, they are either added as a material to the image component of the canvas (but the problem is that they are too voracious (it is necessary that the blur process works fine on mobile phones) and the quality of the blur itself is not very good), or they are hung on the camera (for example standard blur from the unit) and blur only the objects of the game world, while the ui remains in its normal state.
So here's how to make a blur ala ios, and so that it does not lie down on mobile phones. Maybe there is a ready-made shader code (to make a copy-paste, otherwise I understand them only superficially), or there is some other blur technique. Thanks in advance

Answer 1

Once I did it like this: https://mopsicus.ru/all/unity-blur-effect-2-cameras/
But they rightly say that it is quite resource-intensive