I suspect so. But depending on jurisdiction it may not be waivable. Or the ToS may be drafted in a way that doesn't cover this.

Not to mention violation of the copyright of the website (and other rightsholders):

• derivative works

• public performance

• willful infringement

• GPL violation

• patent infringement

I wonder if there is some way to devise a website that implement a copyright protection technology that js injection circumvents.