There's more to it as well, such as:

• investors coming back from vacation and selling off losses and whatnot
• investors expecting reduced spending between summer and holidays; we're past the "back to school" retail bump and into a slower retail economy
• upcoming election, with polls shifting between Trump and Harris

September is pretty consistently more volatile than other months, and has net negative returns long-term. So it's not just the Fed discussing rate cuts (that news was reported over the last couple months, so it should be factored in), but just normal sideways trading in September.