Well, this is an interesting one. One of the big highlights of the Canon EOS R3 was that out of the various Canon “firsts” it was celebrating, one of them was a brand new Canon BSI stacked CMOS sensor. All of the promotional material from Canon UK even said “designed and manufactured by Canon”. This wording seems to have changed, though.
Now, the wording on the Canon UK website now simply reads that the sensor was “developed by Canon”. And an interview between Russian photography website PhotoWebExpo and Canon Russia’s Head of Product and Consumer Expertise, Andrey Tischenko suggests that while Canon may have designed it, it might just be Sony that’s making it for them.