Nothing. These are rules of the Senate so they can be changed at will whenever they choose. Well, within the rules of the Senate that covers changing the rules of the Senate.
But since it was done, it'll be easier to repeat it in the future. Which was why most wanted to avoid doing it over the years.
The fact that the Senate rules are adopted for each new session, at the opening of the session, by a simple majority vote stops that from being meaningful as a tactic (nothing stops them from doing it, but it doesn't do any good.)
But since it was done, it'll be easier to repeat it in the future. Which was why most wanted to avoid doing it over the years.