Is Canon Set To Release a RF 5.2mm f/2.8 Lens?

Not sure if this is a typo or if it is real. Canon might release a RF 5.2mm f/2.8 lens for the EOS R system, a usually very reliable rumor source suggests.

Nokishita tweeted that Canon might be set to release a RF 5.2mm f/2.8 lens. A fish-eye lens, I guess. Nokishita says:

Canon’s next RF lens will be 5.2mm f/2.8L. Check Canon’s latest accessory list for unreleased lens caps 5.2.

As far as I know, such a lens has never been rumored. What do you think? Real, or something got lost in translation?