He did more testing, and there are a lot of interesting results. In some games tested at 1080p, (Starfield and Warhammer) there was no dropoff at all with the 4060 until you get to the 3600. In other games there were some.
And in Spiderman there's a very strange situation with the 9800X 3D where the B580 gets +35% performance for some reason compared to the CPU tier below it.
The issue seems to come into play when going below a Ryzen 3600 (3000 series). Since the RTX 4060 seems to have a similar dropoff when going from a Ryzen 5600 to a 3600.
But the RTX 4060 being notably better than the B580 on a Ryzen 3600, and in most of the games tested on 5600 (except for Hogwarts) makes me surprised I hadn't heard about this before. Even at 1080p.
Just to be clear, were these tests done with Resizable BAR enabled, or not enabled?
(Skimmed through the videos so I'm not sure)