There's no need to test for it at the factory if you're not promising it works. Certainly, the PCB needs to be built for it; but I'm sure some boards are designed for B650E and then put together with a B650.

Regardless, the chipset has been out for almost 3 years. Kind of late to put the horse back in the barn. Regardless of certification, lots of systems are out there where it's enabled, and those with those systems and a pci-e 5.0 can tell us how it works regardless of what the branding says. Maybe it's flaky, maybe it rarely works. Maybe it just made sense to follow the pci-e 5.0 design rules for the gpu slots, even without the branding; maybe the pci-e 4.0 design rules are good enough at the trace lengths on a typical am5 board. Maybe once you have the PCB designed and built to run the cpu m.2 at 5.0, it doesn't cost anything to follow design rules for the cpu x16 slot as well.