Yeah, she is really diving down hard. But, in a way, this is not such a bad thing. Many Fresians are jsut the opposite; head up high. It can be hard to get them to settle and lower their heads.
This is a matter or reteaching her to what the rein means, and not playing in to that 'game' of 'I lean on you, you hold me up". That means you get her to raise her head and not lean on the bit; by asking her to move forward wish a short slap of your leg when she dives to get her to lift her head and move forward more.
And/or by asking with the rein for her to 'come off' the bit. You don't stay in the place where she is comfortably leaning on the bit and you are just 'meeting' her there. when she starts to lean into it, you do something different, rather than just 'holding' her.
That can be a small bopping action with one rein that says "hey, not so hard !". It can be a lifting action of your hands, and preferably using ONE hand much more than the other. It can be experimenting with totally throwing your hands forward, or try throwing one hand forward. It's an experiment to see what she does when you break the cycle of 'you lean on me, I hold you up"