That must have been an error on Steam, because I'm showing their pre-order price is $44.99 USD, same as on the Matrix/Slitherine store. I do see the pre-order price on GOG is $49.99, although goodness knows whether or not that's also correct or a goof.
Oh, and of course, I did go ahead and pre-order this one (through the M/S storefront). It's my first time pre-ordering in over a decade. Fingers crossed it goes better than the last time I did this!