If this was "fair", they should do first in/first out processing of points. (In other words, if I have x points from a rental in 2020 and y points from a rental in 2024, then the x points should be assigned first when I apply them for a free rental.)

I don't have a lot of confidence that (a) Hertz can do this with their systems and (b) they are going to be fair... but maybe others can weigh in and make me less cynical :-)