Talking about this, this is pretty risky for online games which have connection to the server. for example if it is not well optimized then i can get 100,000$ of in-game premium currency for free with typing a little code in inspect-element.
As an online game developer, I MUST care about these sort of stuff to don’t put users’ security in trouble as well as preventing cheating, Tampermonkey hacking may sound harmless as it only runs on browser but it becomes serious if it is highly connected to the server.
Not only you need to make the backend side secure but also make the front-end code hard to read.