CCP altered the mining resources distribution across space as part of their “Scarcity” and “fix the broken economy” initiatives. There has been much debate over whether this is a good idea or a bad idea, or if CCP can even differentiate between the two.
Should get you started on what’s going on there. There’s a lot of opinion pieces from various authors if you google “EVE Resource Redistribution” and “EVE Ecosystem Scarcity phase”.