Without getting too complicated
Mika's brother is the ambassador to Poland where her father came from...and Solidarity (breaking off from Russia) occurred in the early 90's about the time the Bill was running for President.
I don't have a reference, but Brzezinski wanted a missile shield, membership in Nato, and lots of other protections for Poland. Bill Clinton apparently didn't go along with everything, so Carter's National Security Advisor (also worked for LBJ) really went after Clinton.
They haven't been friends ever sense. Mika grew up in that household in the 80's and 90's. I suspect (since Bernie is Polish) that she harbors a bit of favoritism for him too.
She's been on Hillary's case for years. Of course, Joe has made the Clinton's a target for every CT coming down the road. Between the two them, it's really hard for me to watch.