If-and-only-if an actual contract was offered, understood by all parties, and agreed to, then you're free to find them the user in breech of contract. Obviousl

If-and-only-if an actual contract was offered, understood by all parties, and agreed to, then you're free to find them the user in breech of contract. Obviously. And just to be clear, this is the situation in many cases where people have been upset by these changes. None of that is relevant to a tool having any particular feature. Sure it is, if the tool is actively promoting something that will interfere with a lawful contract with another party. The law often recognises this problem explicitly, in many jurisdictions. (If you weren't aware of this, you might like to look up "tortious intereference" as a starting point.) Even when a contract actually exists (a ToS is not a contract), the browser creators are an unrelated 3rd party. They cease to be unrelated when their actions interfere with the first two parties in a way that harms one of them.