

Not only the content doesn’t exist yet, it’s just not practical. Even now 4k broadcasting is rare and 4k streaming is now a premium (and not always with a good bitstream, which matters a lot more) when once was offered as a cost-free future, imagine 8k that would roughly quadruple the amount of data required to transmit it (and transmit speee is not linear, 4x the speed would probably be at least 8x the cost).
And I seriously think noone except the nerdiest of nerds would notice a difference between 4k and 8k.
Probably some guy working on legacy hardware found a bug, fixed it for work and while was there, pushed it.
Or you know, some other guy with a lot of free time dusted off some old cards and wanted to play with them.