This is a weird business. Men get roles at a ration of 4 to 1, and then there are less of them acting. So if they pay in the “fair” way, by experience, then of course they get paid more.
She was in a successful franchise, and so were her male counterparts, and although she was commanding similar box office draw, they were odler and more experienced.
Agents and Managers can do their best, but there’s a limit to how much they can negotiate.
Factor in that when women do have speaking roles, they tend to speak less, then you have a perfect storm.
It’s not an easy thing to fix but I hope people will keep working to fix it.