I already wrote that I don't have a problem with adapted EF lenses. They are older and much cheaper and they work.3rd parties design glass specifically for RF mount cameras, too.
I have had no issues with my EF Sigma 35/1.4 mounted on an EOS RP with the RF adapter.
I wonder if Alex Barrera's problems with the Samyang AF 85/1.4 have more to do with his R5 than they do the lens, and I have read previously that once the R5 updated to the latest firmware, problems with the Samyang were eliminated. I cannot confirm this with my own experience just yet.
EDIT: many commenters on the video are saying that with version 3 camera firmware, the lens works just fine. It may not be a lens firmware issue at all.
But RF lenses with AF not optimised how Canon designed it? No thanks. Might as well go E-mount instead then, there is really no real difference.
No 3rd party manufacturer designs glass specifically for Canon RF. They do a little adjusting but they don't design the lens from the ground up to take advantage of the wider mount, it has to be E-mount L-mount etc. compatible as well.
I mean it is the same as using Sony glass adapted to the Nikon Z cameras. Just why?
They might work just fine but as technology evolves even further they just going to have more problems regarding AF, the colours will be different as well, I just don't think it is worth the savings when Canon does the job of delivering top quality glass ready for even higher-end bodies.
There are cheaper options here and there, but it's not the main focus, for that specifically, Canon / Nikon are not the ones to go for at this point.