Low esteem can in some ways be linked to childhood trauma,neglect or abuse.
When we experience certain traumas in non supportive,empathetic environment,we tend to construct a coping mechanism,that aid in suppressing these toxic memories.
As adults,the coping mechanisms,come under stress and struggle to maintain order,which can result in depression.
The earlier traumas,can no longer be contained and require some kind of resolution or release.
This in itself,emotional clearing, is very difficult work and is best done with a professional who is trained in this field.
If you want to read about this topic,then John Ruskan’s book might be a good place to start.
All the best,hope this helps!
https://www.amazon.co.uk/Emotional-Clearing-Releasing-Awakening-Unconditional/dp/0712671676/ref=cm_cr_arp_d_product_top?ie=UTF8