It's an interesting world in terms of the way and sense in which things work; HDMI 2.0 is now non-existent and has been absorbed into the HDMI 2.1 naming.
The HDMI 2.0 standard was phased out by the group in 2017, and display manufacturers should continue to use HDMI 2.1 in the future — even if it lacks some of the essential features of the newer standard. A statement from the HDMI Licensing Administrator was forwarded to TFT Central, which explains a thing or two. Shortly put, the HDMI 2.0 standard "doesn't exist" any longer, and display designers should indicate that any HDMI 2.x display supports HDMI 2.1, provided that the display supports at least one of the two new features. According to the statement, the features of HDMI 2.1 are optional, and display manufacturers are required to list the features that each display supports.
TFT Central discovered a Xiaomi 1080p 240Hz monitor that claims to support HDMI 2.1, despite the fact that the port only supports the specifications of HDMI 2.0 and not HDMI 2.1. We're not likely to see the end of these "fake" HDMI 2.1 monitors anytime soon, and the HDMI Licensing Administrator doesn't appear to have a problem with that either. Although HDMI 2.0 and HDMI 2.1 are quite similar sounding in name, they are almost entirely different generations. In comparison to HDMI 2.0, HDMI 2.1 can support nearly three times as much data, allowing for higher resolutions and refresh rates. It also supports features such as variable refresh rate (VRR). To fully utilize the capabilities of HDMI 2.1, a special high-speed HDMI cable must be used in addition to the standard HDMI cable.
The HDMI Licensing Administrator does not believe there is much of a distinction. HDMI 2.0 was deprecated in November 2017, according to an email from the group. The features of HDMI 2.0 are now a subset of those of HDMI 2.1, according to the group. In other words, as long as the monitor supports one HDMI 2.1 feature, it supports HDMI 2.1 on a consistent basis. The increased data transmission speed of HDMI 2.1 is also taken into consideration, which means that ports that operate at HDMI 2.0 bandwidth levels can still use the new name as long as they support at least one feature. That is a significant issue. There are nearly too many new features in HDMI 2.1 to list them all, but some of the most notable are eARC, VRR, Display Stream Compression (DSC) for higher resolutions, Auto Low Latency Mode (ALLM), and support for dynamic HDR, to name a few. When you add support for one, the display is eligible to claim HDMI 2.1. Those of you who have upgraded to a PlayStation 5 or Xbox Series X gaming console will be familiar with this problem. HDMI 2.1 supports some critical gaming features such as ALLM and 4K at 120Hz, as well as 4K at 60Hz. The standard — HDMI 2.1 — is supposed to include those features so that customers don't have to wade through a slew of technical jargon to figure out whether or not they're purchasing the correct item. It doesn't work like that.
HDMI is both a port and a standard, and it is used in a variety of applications. The addition of a new number should be significant, but under the current guidance, it is not required to be so.