For a bit of context I’ve been NC for some time with my mother. You’ve said that you don’t understand why your daughter might be ghosting you and communication has broken down.
For me it took a long time to come to terms that I couldn’t go on having a relationship. I wasn’t listened to, boundaries were trampled on and there was emotional and financial manipulation going on. Demands were constantly being placed on me regarding my time ( to spend more with her after she divorced my dad ) although it was incredibly difficult to spend time with her as I was walking on eggshells all the time.
It got too much, she wouldn’t listen to me trying to tell her about anything and it came to a head when she was challenged about a situation. None of it, predictably, was her fault and she’d taken decisions regarding aspects of my daughter future without consulting me. I cooled things rapidly to try and see if we could work through it later and decided not to after receiving a letter which was basically her calling me all sorts of things.
Only you can know what has happened in the past. The end situation brought about the NC with me but it really was a build up of a lot of things that weren’t right - but maybe some of the things I’ve detailed might give you an insight if you unpick your relationship from your side about what may have gone wrong between you. I’m certainly not a saint, but for me and my mental health, going NC was the right choice.
As for birthday / Christmas, the cards I receive go in the bin now, she isn’t really interested in making any changes to herself and they feel more about her than me as she’s still not acknowledging my boundaries. Any cash gets spent on my children.
Presents for my children are just another attempt to emotionally manipulate. She will only see my eldest ( older teen ) if she’s got something to hand over to me or the others. And as she’s off to uni soon stated to her that she’s lost her middle man and to tell me that if I wanted gifts for the little two I had to call her. ( on the flip side if she really wanted to gift things for her grandchildren she could make arrangements ). I’m not calling.
As others have said though it isn’t a decision taken lightly to stop contact with a family member, and if you do want contact to resume you will have to be patient and wait for her to come to you.