This appears to have leaked 2 days ago, but I did not see it here. I don't know about the veracity of the site but they seem to have good information complex with a pictures:
Note: all the links to Amazon in the article are no longer valid so it was taken down.
First few lines from the article:
Canon RF100-400mm F5.6-8 IS USM up for Pre-order on Amazon US - Online Shopping USA - Deals and Offers
Canon has launched RF100-400mm F5.6-8 IS USM lens for their EOS R Series cameras in the US. It has a launch price tag of $649.99. This RF lens is now
usdealsoffers.com
Note: all the links to Amazon in the article are no longer valid so it was taken down.
First few lines from the article: