So I looked at the output for the R5 and found this article:
The quotes that stood out at me are:
If there is one compelling reason to look at the EOS R5 it is that it can record fully oversampled 4K footage taken from an 8K source. This alone means that 4K recorded with it gives a multitude of benefits over native 4K recordings taken from lower resolution sensors.
There's no ProRes RAW output from the new EOS cameras. It's conjecture as to whether this is even possible. However the EOS R5 and R6 are unique in Canon's lineup in that they are the first mirrorless cameras that the company has produced that will output a clean full-frame, full sensor width readout 4K 10-bit 4:2:2 video signal at up to 59.94p over HDMI.
Someone said in the comments that the Atomos helps with the potential cooling problem on the R5 too. Now the question is should I be recording 10-bit 4:2:2 RAW at (usually) 24 fps? That's a lot of storage and processing for my laptop.