I have similar problem where my mango tree is not growing. new foliage becomes wrinkled and black spot.

I have it in a 45 gallon pot with mix of soils and compost. and the tree is 4 feet. Any sugg

Thank you

https://www.straitstimes.com/lifestyle/home-design/root-awakening-mango-tree-may-be-suffering-from-a-bacterial-disease

That new growth on that mango tree looks as if it has anthracnose which is a fungal infection I believe. You can probably treat it with copper fungicide. As for blackening leaf tips, I noticed that when I had an indoor mango tree. it is typically caused by too high salt in the soil. I would water with distilled water. I would also give it more humidity