"HDMI Forum Rejects AMD's Open Source HDMI 2.1 Driver Proposal"
The HDMI Forum has rejected AMD's proposal for open-source HDMI 2.1 driver support, leaving AMD's open-source Linux graphics driver unable to implement HDMI 2.1+ functionality due to legal requirements. This means that for the near-term, there is unlikely to be any HDMI 2.1+ feature support in open-source drivers, and open-source supporters are advised to pursue DisplayPort for the best experience.