The Mandela Effect

[ArMaP]

I just seem to remember from the 90s the big thing being "does mars have water?" and then it was "ooh look it does but its all trapped in the poles under the surface" and now it's right there floating in the sky where presumably an orbiting spectrometer could have seen it decades ago.

When the ice on the poles melts the water turns to vapour and creates clouds, like on Earth, only much thinner and only at high altitude.