It’s a double edged sword and not just all benefits and no costs or risks, which will take several lectures to just scratch the surface.
China keeps careful control on the RMB for very good reasons, which is why it’s not desperately keen for the RMB to just straight replace the USD, as that would trade one problem for another.
What it is doing is removing the USD from its own bilateral trade with the RoW, but it has no interest in actively promoting that the RMB he used by other countries doing trade with each other.
China also cannot simply create a separate international trading currency, as that will basically carry much of the same risks and costs as just straight using RMB.
The ideal solution, which is what China is trying to push, is for the whole world to accept a common universal trading currency that isn’t linked or dependent on any single nation. That way all countries can essentially separate the often conflicting internal and external monetary policy priorities and pressures on their own sovereign currency supply and demand dynamics.
This is why it continues to tolerate India. Because for such a currency to work, you can’t just issue with to and between friendly nations. I think the rational is that if you can develop a framework that will satisfy the Indians, you can easily build upon that to satisfy just about anyone else.