I thought it was being pushed now because mkopec managed to implement a partial, clean room reverse engineered version first using register captures from the Windows driver.

I've been using linux with 4k120 tv with amd gpu for about half a year. dp to hdmi 2.1 cable works without issues.

What content is streaming at 120hz? Otherwise, 4K 60hz HDR is fine on 2.0

Try Linux on a 4k HDR 120hz TV and see what happens.

It works fine, with chroma subsampling. At least I personally don't ever notice it on the TV.

That's not to say this getting fixed isn't important, but it's mostly relevant for monitors and maybe smaller TVs that you sit closer to.

LPT: Your Shield can run Lineage OS