Looks like the prices on steam for non NA players had a HUGE increase in price with no previous announcement.
To put things in perspective: here in Brazil I used to pay 28,99 BRL for a month worth of gametime, this price was just adjusted to 41,99 BRL, which is a 45% increase!! 1 month after the expansion launch and with no announces.
Prices in Russia have also increased, according to some it was an increase of above 200%!
EDIT: the prices got adjusted right after the servers came back up after the 4.05 patch update.
And here is the official answer:
TL;DR: Square decided increasing the prices for players of some regions on steam, steam itself had nothing to do with it(as many are wrongly assuming), since steam is nothing but a portal for you to buy games, they don't set the prices, the game publisher does.
----------------------------------------------------------------------------------------------------------------------------
Also, something extremely usefull:
----------------------------------------------------------------------------------------------------------------------------
And youtuber SidAlpha made a very good video covering all of this:
https://www.youtube.com/watch?v=dXXjJE0kQtY