Basically in a nutshell, Jared was super impressed with the raw files, although the camera was underexposing a bit when compared to what the new viewfinder was showing him. He needed to raise the image exposure in Lightroom by 1 full stop pretty much. Sony cameras are notorious for underexposing about 1/2 a stop based on my experience over the years, and I was thought it was to preserve the highlight detail at all costs. Every camera manufacture has their preferred metering algorithms though, and Sony’s is clearly on the preserving highlights side of things when compared to other camera manufacturers. Jared seemed to think the viewfinder was more the reason in this case however, so this is worth taking note of.
As far as the Sony A7R IV being a medium format killer, Jared says no it is not. The medium format is a much larger sensor and it produces different images. It would be better to say the Sony A7r IV has the best image quality out of a full frame 35mm digital format.