Why Did Amazon Partnered Carrier Rates Double for the Same Shipment?

size to Amazon using their partnered carrier, and it cost me $60. Now, for the exact same shipment (same box size, weight, and quantity), the cost has jumped to $117.

The only difference I noticed is that Amazon assigned a different fulfillment center this time. Could this be the reason for the price increase? Does warehouse location affect partnered carrier rates that much?

Could weather or other factors also be causing this? Has Amazon recently changed its shipping rates?

Also, is it worth waiting to see if the partnered carrier rates drop, or should I look for a better deal elsewhere? Any advice would be appreciated!