For stuff like connectors, this gets worked around by using terminology like “compatible with HDMI” all the time. You are explicitly permitted to reference your competitor’s products, including potential compatibility, by trademark law. I suspect the risk here is mostly contractural - AMD likely signed agreements with the HDMI forum a long time ago that restrict their disclosure of details from the specification.

Im shocked i had to scroll so far to find a real hard stop blocker mentioned.

Valve has no reason to care about using the HDMI trademark. Consumers dont care if it says HDMI 2.1 or HMDI 2.1 Compatible.

The connector isnt trademarked and neither is compatibility.

The oss nature of isnt one either as valve could just release a compiled binary instead of open sourcing it.

The 'get sued for copying the leak' argument implies someone would actually fancy going toe to toe with valves legal team which so far have rekt the eu, activision, riot games, microsoft, etc. in court.

Proving beyond doubt that valve or their devs accessed the leaks would be hard. Especially if valve were clever from the get go, and lets face it, they probably were. Theyre easily one of the leanest, most profitable, and savviest software companies around.