I too have struggled with this question, apologies if this response is too personal.
I had repeated surgeries throughout my childhood which have shaped me and led to my current difficulties. Any time in hospital for a child, away from carers must be upsetting, but clearly it can't be abuse because the 'intent' is good. That's what I was always told at least.
So when I was being held down and forced fed foul medicines, restrained whilst they removed stitches from my genitals without anaesthetic, having my penis sprayed with a freezing aerosol to prevent erection following treatment, photographed naked, having sutures cut deep into my genitals because they didn't allow for swelling, and so on, over the course of 13 years etc.etc. I had to accept it because I was repeatedly told it was for my own good, the intent was good, to make me better.
So I never did complain, or told my parents about the way things were sometimes done (not always), that hurt or humiliated. I never told them about being smacked in front of other children on the ward by a nurse for wetting the bed, or being molested and sexually assaulted by a medic, because I was told it was necessary treatment, and why wouldn't I believe that, after years of medical treatment, I still believed the intent was good, so I cooperated.
I guess at best it was at times traumatising, at worst abusive, but who decides or defines?
It was this confusion and lack of clarity, was it abusive, traumatic, is it ok to say I was affected, am I being ungrateful....? that kept me quiet throughout, and for the next 40 years, whilst I quietly internalised the experiences and evolved harmful ways of dealing with it that have been truly disruptive and damaging to me and my family.
I still don't really know how to define child abuse that fits with all potential situations.
Sorry if this is rambling. Still raw after 40 years.