We don't see evidence of a stem borer (their tunnels would be quite prominent), though the discoloration of the branch heartwood is either due to infection or natural, it's hard to tell from the photo. Flaking bark can be normal on mature redbuds, or it could be a sign of a problem in the wood underneath it; by itself, it's not diagnostic enough, unfortunately. How the canopy is faring is a better indicator of a problem...can you share a photo of the entire tree? Is it in decline, with major limbs dying back, or does it look fairly normal and full?

Redbuds are not long-lived trees compared to canopy species like oaks and hickories, and about a 20- to 30-year life span is typical for those grown in most environments. Not all ailments they might accumulate in that time are treatable, such as Botryosphaeria canker, a common fungal disease that preferentially attacks trees and shrubs that have been stressed, such as by drought. (The page linked focuses on Rhododendron, another common victim of that kind of infection, but it applies to other host plants as well.) Wood-boring insects, which can afflict redbud but which we don't see here, also tend to target plants that are stressed, even if other symptoms of that stress are not yet obvious.

Although probably not necessary since there is little intervention possible if the tree is in decline, you could have it evaluated by a certified arborist or licensed tree expert. They can't cure or treat every condition, but can help to narrow-down a potential diagnosis while also looking for sources of tree stress that might be able to be alleviated to prolong it's life. Lots of paving materials surrounding or close to a root zone, for example, can limit moisture and nutrient resources for the roots and might be contributors to long-term stress.

Miri