International law in this context just means that a single global hegemon can no longer push everybody else around and call it's will and interests "law" and therefore it's interest somehow benevolent. That is exactly what "rules based intnernational order" means.
Not that we have ever had any law that equally applies to everybody equally. All laws and even international law needs a hobbesian Behemoth that is more powerful than any other to enforce "international law" and is in the end above it since it is at the best position to enforce and set the "law". The UN and it's institutions are basically basically a discussion club by design and it can't do shit so post 1990 world the Behemoth has been the world hegemonic United states. Now that US has declined relatively as Russia, China, India, Iran, etc have risen it finds itself unable to enforce anything through hard or soft power and therefore the idea of law, stability and peace under US dissipates. Not that it was ever lawfully, peaceful or stable, that illusion only applied to the western core nations of this now dead American world.