Citi card Thank You notes/points reward cost change over time?

So I signed up for a Citi Forward card to supplement my Chase Freedom (rotating categories) during the crappy categories. I figured between the 5 points for restaurants and (supposedly) amazon.com all of the time will suit my needs the majority of the time for a good 5% cash back.

However when I signed up for the card, I checked the rewards and saw Walmart and Amazon.com (both same as cash to me) were 10,000 points for 100 for each...Now i see that it's not longer a 100:1 ratio but more like 6500 points for $50 etc

My question is, how often do they normally change the price of rewards, and is it normal for them to run 10000:$100 Amazon/Walmart gift cards or is it normally 6500:50 or whatever. I feel slightly ripped off because I signed up with the assumption that the 10,000/$100 was the "normal" price and not some special / point sale. Anyone have any experience with this? I flipped through a few categories and there really wasn't anything that was at a 100:1 ratio so I'm not really getting 5% on restaurants/amazon.