I haven't seen a weight on the 70-200 RF yet... The interesting question will be how much lighter (if any) it is than the comparable EF lens. The Canon RF 24-105 is about 15% lighter than the EF equivalent, the Z kit lens is 20% lighter than the Canon 24-70 f4 DSLR lens (It would, of course, be better to compare Nikons to Nikons, but Nikon doesn't make a 24-70 f4 for F mount), and the new 24-70 f2.8 Z lens is close to 1/3 lighter than the 24-70 F mount Nikkor.
Will the compact Canon 70-200 have a similar weight reduction compared to Canon's 70-200 f2.8 for EF mount? If it's just collapsible, but of conventional weight, that's still an advantage - it looks like it might fit in 24-70 slots in many bags, or it might fit in 70-200 slots, but with the hood on... If it has a weight advantage, especially if it's towards the 30% end of the scale, that's another advantage.