Facebook should try to adapt screamer-prank tech[0] for ads. Even if an ad missed your attention, you'd still have to pay 1 laundry bill and 1 bill for stuttering-aid couching.

Jokes aside, even with rendering to canvas, ad can be blocked with image recognition. Long time ago I used Sikuli Script for UI testing automation, Sikuli recognized parts of screen and worked very fast; combine it with an app like CinemaDrape and voila.

[0] (loud noises warning) https://youtu.be/469zNXTCHdk?t=10