Jeffers red maple disease? Rot?

My Jeffers red maple, planted late winter 2024, began to drop leaves mid summer last year and some branches seemed to harden. Those branches did not regrow leaves, and are now brittle.

After pruning some of these branches, I noticed the issues internally within the branches.

What could this be? Disease? Rot? Both?

I’m in zone 5b

Anything to do other than prune?

This plant is in an area which receives water via sprinkler during the late spring through early fall, 3-4x per week. It gets full light.