My guess would be that this is a bug, though I can see an argument either way. The patch notes do say "- Re-enabling yield for canyon plots (2 production, not improvable", which I suppose could be interpreted as meaning that the tile yields can't be improved by satellites. That would be an odd use of terminology though, since improvements in BE are specifically something that workers build on tiles, and that they are, of course, unable to build on canyon tiles.
It would seem especially odd for "not improvable" to mean "unable to be enhanced by any means" when there is now a wonder whose sole function is to add production to canyons. I haven't yet built the reworked Tectonic Anvil, though, so I don't know whether the 5 production per canyon is added to the canyon tiles or to the city itself. Is there someone who has built it and can comment on this?