retroactive lengthening of copyright
Yes. It's like you've paid money into a pension fund with the understanding that you will receive a pension when you reach 65, but suddenly Disney and Co decide that you should wait another 20 years ... in order to better protect their rights.
The copyright extension from 50 to 70 years that took place in 1995 in many EU countries should be declared illegal, invalid and not applicable to works published before 1995.