Carrying a lot of cargo gets you pirate attention now.
If you jump during an interdiction then the interdictor is dragged with you and insta-win when you get to the next system since you were tethered and the stress on the FSD forces a drop out, unfortunately that drops you near a sun.
The way to avoid is to quit hyperspace and play the mini-game or submit.
You probably got lucky, in my experience the NPC pirate will continue the attack after jumping, a little repair from heat damage is probably less than what the Anaconda would have done...
I do agree though, interdiction should give bounty to all except police, were you or did you jump into anarchy system?
That just seems wrong. It didn't used to be like that - Jumping was a valid interdiction evasion technique (if you were already charging at the time). "Dragging" another ship along should increase the fuel needed beyond the FSD capacity. Wrong.