An image and some specifications for the Canon RF 100-400mm f/5.6-8 IS USM have leaked out ahead of next week's official announcement. I will note that the lens is a bit slower at the long end than my original report of f/7.1.
This lens looks to be extremely compact for what it is.
The Canon RF 100-400 f/5.6-8 IS USM has a minimum focusing distance of 88cm at 200mm, a maximum magnification of 0.41x at 400mm, and up to 6 stops of IS when paired with the EOS R5 or EOS R6. When using this lens with the EOS R or EOS RP, image stabilization is about 5.5 stops of correction.
Another interesting design choice is that this lens is compatible with both the RF 1.4x and RF 2.0x teleconverters. Canon has also added a dedicated control ring to the front of the lens.
The Canon RF 100-400mm f/5.6-8 IS USM will be priced at $649 USD.