It looks like Canon may have one more lens to announce in 2021. They have registered a new and unreleased lens, with the product code 5554C005AA.
The latest Canon lenses to be announced the RF 16mm f/2.8 STM has the product code 5051C005 and the RF 100-400mm f/5.6-8 IS USM is the 5050C005.
I don't know for sure which lens is being registered here, but if I had to wager a guess based on the Canon Rumors RF lens roadmap, I'd go with an RF 35mm f/1.2L USM. Again, that's just a guess!
I would think a 35L would definitely create enough hype to be announced on its own.
More to come…