There was a backorder list over at Canon? That these lenses were short in supply has been known since their launch, but it turns out that Canon has an official supply shortage list (here). The recently announced 14-35 f/4 starts off on it.
The “big white,” still-unreleased, RF 400mm and RF 600mm f/4 are also already on it, along with the 100mm Macro f/2.8 that is expected to start shipping tomorrow.
To round out the list the ever-elusive 100-500 of course tops the list.