It's just variation in the genes of seed raised plants. I expect a breeder might try to produce a new strain with upwardfacing flowers, but that would mean losing a lot of the charm of foxgloves.

First rain and they'd rot. Good one! Do the bumble bees still visit the upward ones?

Maybe they're from down under "aussie" ones

... or, given that we've all been experiencing photos which upload, upside down, on this site, perhaps this plant is one step ahead of us and is adapting to suit the new conditions?!...