I'm LC with my DM.
I don't ask to speak her, I wait for her to come to me and then do the nod, smile, more tea? type conversations with her that keep her at arm's length. I send birthday and Xmas greetings and discharge as many duties as I can from a distance. We chat 6-8 times a year.
I think it probably upsets her that I "grey rock" her. But I'm not really sure what else I am supposed to do. She's spent her life making choices that hurt, disadvantage, even devastate me. I've confronted her once or twice, very gently, and she dissolves into tears and accusations and self hatred, she will say anything she has to say to get me to shut up and just keep taking care of her.
She had a dreadfully abusive childhood and I know that's probably why she is the way she is. But I can't help her with that - I tried, the more one tries to help, the worse it gets. And eventually it became clear to me that I was draining off my energy to her, at the expense of my DC. Just couldn't do it anymore in good conscience.
What would it take for me to go to normal contact? She would need to start to:
Ask me how I am.
When I reply, actually listen, show care. The last time I told her how I was feeling, during a time of extreme pain for me, she visibly stiffened and changed the subject. Times before that, she'd interrupt to ask me why I hadn't xyz, did I try abc, etc. while ignoring my anguish. Painful.
For her to become a grown up, who participates in life with me.
None of these things are going to happen. DM doesn't even know that she could be different - she is a mess of blind spots and denial.
I often see the undertone in threads like these of, "well I was just a bit useless, I didn't know any better, why is my child so angry with me for just being human?"
The thing is though that sometimes, in "just being human" you may have absolutely broken your DC's heart. The fact that you didn't mean to doesn't mean anything. Their heart is still broken, they still feel like running away when they are near you, what is the DC supposed to do? Sacrifice their mental health for a parent who was too "useless" to notice they were doing a terrible job? It is such a rock and a hard place for the DC.