I've been playing RS for decades now. I upgraded to the new launcher. Wish I hadn't. I have never seen a buggier piece of code than this.
Flush your cache. Uninstall and reinstall. That's some Microsoft BS. Do better Jagex. If one player is having a problem, I understand. But I'm guessing a large percentage of players are having the problem, so fixing it is clearly on your doorstep.