We can not tell exactly which fungus this is as our plant pathologist is out of the office today, but we don't need to know to tell you that it is growing on dead wood within the tree. The tree looks like it has tried to recover from a large area of old injury, but it is not doing well, as you can tell by a large barkless area where the primary growths are. This could certainly negatively affect it's structural integrity.

How does the canopy of the tree look? Full and green without dead limbs?
If it looks healthy and is important to you, we'd suggest an on-site evaluation by a tree health specialist referred to as a certified arborist for an on-site evaluation. You can search for a certified arborist at www.treesaregood.org

If it's fall would endanger people or property, you should consider prompt removal. Here is our page which helps you decide when a tree should be removed: https://extension.umd.edu/learn/how-do-you-decide-when-remove-tree

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