Q.Why My Museum Palo Verde Tree Isn’t Getting Taller?
The tree is very healthy, blooming width wise and full of blooms. It just won’t grow taller.

Certified GKH Gardening Expert
This could indicate that something isn't quite right about their environment. Unfortunately, your photos did not come through, and There isn't much information on the environmental conditions surrounding the tree.
In the meantime, this article will help you to know what kind of care these trees require:
https://www.gardeningknowhow.com/ornamental/trees/palo-verde/palo-verde-tree-care.htm