Exactly. In civ5 tundra is somehow a huge biome where entire civilisations may fit in, while this is the map of extent of real tundra on Earth [emoji14]
Please note the entire population of those areas in real life is less than one million, so actually civ5 tundra is proportionally much more inhabitable than real life tundra.
Tundra shouldn't have some magical use in civ6 because well for the entire human history it sucked terribly, as MadJinn mentioned, no great civilisations ever arose in tundra or far north because those lands are simply physically bad for humans and vegetation.
There is not a single example of civilisations flourishing in polar regions, and those few countries that are at far north (because somebody has to be [emoji14] ) - Canada, Russia, Norway - all have extremely small population density, with all population living in the non-tundra lands.
And don't bring Inuits as an example. Inuits have millions of square kilometres to inhabit, yet their population is iirc less than miserable 150 000 people, and they all live in the warmest, fringe parts of polar areas. Their adaptation to that climate didn't mean they flourished here, but that they were able to biologically survive and maintain their extremely low numbers living in small tribes without urban centres etc. That's a society, but not a
civilisation.
There are also no tundra-specific city districts or tile improvements - research stations are nonsense, as if every random barren area of rocks and snow had magical science abilities but biologically richer lands not [emoji14] And mountain resorts are nonsense too, as if far north of real life Earth was covered in hundred thousands of square kilometres of tourist resorts [emoji14] (that's the scale of civ maps)
IMO tundra/snow lands should be reduced in size to end up similarly as real life Earth shown on the image, and their only purpose should be mining resources and
maybe very occasional research stations.
Of course that creates the problem empty areas of map by the late game, but this could be solved with for example special type of settlements buildable in polar areas that extend borders and allow resource mining but cannot be developed as normal cities.