Adapting Canon EF Lenses to RF Body

[MrDeadpool]

I recently got an EOS R8, the specs on the EOS R8 features a class-leading autofocus system. It shares almost every spec with the EOS R6 Mark II.
so being that both are RF Mount Full Frame, Mirrorless Cameras. Most comparisons say that the R8 Auto Focus is Fast and Accurate as a Camera twice it's price.
So, what do you loose when you "Adapt" an EF Lens that are made for Canon APS-C Cameras to the EOS R8.