Clearly you're already familiar with forest pansy. LOL! No idea what's going on with your pictured one though. Do you have a theory about what happened besides knowing you didn't hit it with mower or trimmer? When did you notice that?

The picture is blurry... could the damage be from deer rub?

It has been a gradual thing on the trunk, and no deer. My best guess is that it's cold damage, but then, I know so little about tree diseases. My other f.p. redbud, set out at the same time, is fine. I'm trying to decide whether to keep the tree or not...

I see a hole which is perfect insect entrance so I'm afraid the days are counted on your FP redbud. I had a gorgeous specimen that died suddenly. Plus redbuds in general are short lived.

I've seen quite a few FP with trunks like this. Makes me wonder if they are prone. Both the FP at my work have this type of trunk damage and we had a horrible winter here in North Alabama.

I don't know what kind of redbuds I have, but the one in my front yard has this kind of damage to the trunk and some limbs. The tree is over 15 years old and the damage does not affect the bloom or growth of the tree, so I've never been concerned about it. If you want to know more about the problem, take your picture to a local nursery and see if the folks there are familiar with it. I've had great luck doing that. I can highly recommend the staff at Green Thumb in Montgomery. I've taken insects twice and a bag of weeds for them to identify and help me find a solution.