A fraction of a stop isn't important, but Canon lens advantage is the way its render. 85 1.2L is still beloved despite there are so many flaw compared to modern design lens such as Sigma 85 1.4Art. A new 85 1.2 RF with faster AF, better built, and corrections of CA will be appreciate for their new EOS Pro camera for those who want it.I'm sure some will, but not many. A fraction of a stop is not, IMHO, such a big deal.
I don't have the sale number from Canon for any particular lens, but they wouldn't be making it if it's not in their interest to do so.