My walmart started doing the same thing with their Great Value spices. I switched to the mexican grocery store down the street and got a bag of cinnamon for like 2 bucks that's 3 times the size.
Read an article saying shrinkflation is hitting the grocery stores hard now, not just snacks. Even the cheap store brands are getting smaller and pricier. Did you check the size of the bag before you bought it?
Hold up, was it the store brand or a name brand like McCormick that went up? I noticed the same thing at my spot last week - the generic cinnamon was $1.25 and the fancy one was already $1.50. Did they also shrink the bottle size or just bump the price straight up?