Have cut it right back but have noticed the new growth and the leaves are part green but mainly black. Initially, I saw white marks on the black branches that spread and now the branches are black.
Leaves and Branches Are Black
Certified GKH Gardening Expert
This description could be insects and or fungus issues.
Generally infected material should be trimmed away and disposed of.
Neem Oil is a good treatment as is works as both an insecticide and fungicide.
It is also safe for people, pets and bees.