Puglvr, I'm sorry yours also got the same problem. I really hope it's nothing serious ... and yes definitely hope we all can find out what's bothering them. Perhaps those who have mangoes here might have the same problem? Any idea what it is? I don't know if some variety of mango is more susceptible to diseases. This one happens to be the Nam Doc Mai which had a lot of white spots before I cleaned it all up and pruned it.

Where did you get your tree from? Home Depot? I wonder is the issue is the roots i.e. Rootbound.

They look like they're a fungus. What's the growing conditions/climate like for them?

It looks like BBS but Anthracnose can occur together with it so it's possible to have a mixture of both. A copper fungicide can be used but it's good to avoid conditions that favour infection. Watering should be done right at the base of the plant, not on leaves or branches. Trees should be pruned so you don't get dense foliage and restricted air movement. This also minimises rubbing together of different parts of the tree which would open up pathways for the infections to get a hold. When pruning frequently sterilise the pruners with something like bleach. You need to remember that these things are in the air around us all the time and only get a hold when conditions are made right for them.