It sounds like you've taken a deep long journey into the mess here: I'm curious, what does it take to be a member of the club?
I hope it's not just FAANGs and blessed hardware OEMs...but it also sounds likely it must be, you can't let just anyone in if you're worried about the specs leaking...but then again that sounds weird too, in that, they used to provide the spec more openly until 2.1?
HDMI adopter registration details here[1]; in general, $10k annual fee + royalties and of bunch of legalese. Prevailing list of 2451 adopters and affiliates here[2]; yes, AMD (listed as unabbreviated Advanced Micro Devices) has been a registered Adopter since Aug 2006 and is currently listed as a 2.1b licensee.
I hope it's not just FAANGs and blessed hardware OEMs...but it also sounds likely it must be, you can't let just anyone in if you're worried about the specs leaking...but then again that sounds weird too, in that, they used to provide the spec more openly until 2.1?