For us, we felt like we had to pursue a diagnosis to try to get DD2's needs met and to prevent us from being fined for school absence, and so that she could be prescribed medication to help with anxiety.
She was never disruptive or naughty at school and had very good attendance throughout primary school but but found secondary school completely overwhelming and became very anxious about school, particularly as she started in 2020 when there was so much disruption and then much of the fun or bonding extra curricular stuff wasn't happening. Not the least in the anxiety about school was that there was so much homework from the start and so much to remember, and there were detentions for forgetting equipment or homework. Also I think the "zero tolerance" approach where she could see other kids being told off and shouted at made her feel so anxious about getting things wrong herself. We of course tried hard to make sure she had everything but it just felt so much harder than with DD2 who went to a super-selective grammar and who were so much more relaxed and had far less homework! I never had a detention at school and was very academic but how most schools are run now would have made me a nervous wreck as I was really scared of getting into trouble. and We tried two different schools but what she really needed was somewhere smaller and nurturing without too much academic pressure (like primary school really) but that didn't exist- even the local private schools are mostly very academic.
It also very common for girls not to have any issues until puberty and secondary school. We are now doing online school and tutoring and hope she will get on better at FE college - the one she wants to go to is quite small and tries very hard to be not like school at all.
We don't do "gentle parenting" but we do kind and respectful parenting for the most part- certainly not authoritarian and carrot rather than stick, but there are good boundaries. Secondary schools are for the most part, not kind and respectful environments. Secondary schools now are just too big and it feels unsafe for many kids and they cannot learn in that environment. And as DD2 was bullied and sexually assaulted, and then bullied about being sexually assaulted, it really was unsafe.
DD2 is not someone who struggles socially or with other activities outside school and does not have general anxiety. It really was just school itself which was the issue.