Up to 25 years means max, which means before the plea deal her max prison time was 25 years for a pre-meditated murder?
It all depends on which state you're in; in some states the penalty for first degree murder is max 25 years (with or without parole).
In other states it's 25 years to life or life with parole or life without parole. Or even death in capital cases.
It depends on the Judge too.
I'm speculating cuz I don't know the details but it appears she was offered a plea of second degree murder, 22.5 year sentence (with parole) so with good behavior she could be out in 10-15!
So she jumped on that, it's a good deal! For what she did.
And it saves the state time and money trying the case they may not even win! Depending on the jury...
To an outsider who hasn't heard all the facts and details, it may sound unfair but there's a lot we don't know.
Our system of jurisprudence isn't the best but sometimes we just have to trust the system.