Exactly. The article says that 90% of hardware doesn't run on it, but in reality, 100% of hardware doesn't run on it. Only Qemu supports it, which is an emulator (and very slow to emulate RiscV in my experience -- latest version we tried with my husband on a very fast PC).
The Orange Pi RV2 was the perfect introductory Risc-V SBC, everyone is going gaga for it, for being a good middle of the road solution for those who want to try Risc-V, and yet, Ubuntu won't support it (and even the current implementation is done by the Chinese, not by Canonical, so I wouldn't touch it).
So I'm not sure what they're thinking. My own conspiracy theory is that EITHER Canonical, OR Raspberry Pi (which are close geographically), are preparing RV23 hardware, so they want to undercut the competition that way.
Nothing else makes sense in that decision.
If it's AV1, you need both the hardware that can decode it, and the right libraries for it. x264 is not the same as AV1. AV1 requires lots of processing power, that's why you see the slow down. But with the right gfx card (and libs), it can decode it fine. What's your gfx card model exactly?