Are you saying that you would come home from work and wake your children up screaming and shouting at them because they hadn’t done the hoovering?
Going NC in my case was a build up of things.
This sort of experience when they were younger all adds up.
Also given the fact you cannot spit out what you need to say is also a thing that can get people close to you deeply frustrated.
If I was to hazard a guess as to the reason your youngest Dd has gone NC i would say you can’t look at one thing that has happened and lay it all on one incident.
Usually there is a build up of many things until something that might seem innocuous turns into the proverbial straw.
I think the incident that you think is minor (whatever it was) is actually irrelevant as it is just another small instance where your dd felt aggrieved... again...and to protect herself NC from these instances is the only way forward
One of the reasons I went NC with my mother was because of her ability to help every other human waif and stray who thought she was absolutely brilliant but when it came to how she treated me there was never quite enough money/support/time to go around.
Have you refused or ignored areas where you could have helped your dc.
Your dd could see it that a stranger comes along and you are all over them supporting and helping them but she wanted something and you weren’t there for her.
This NDN was a grown woman who had a husband. There are 1000s of Romanian immigrants who manage without help. Why were you “helping” when you appear to not have time for your own dc.