No, not sun scald. It is likely a problem with nutrients. But from what you listed, it sounds like it could too much. I would suggest flushing your plants thoroughly and then laying off all ferts for a little while. But I wouldn't get too worked up over the deformation. They look healthy otherwise.
Others may have different advice, but it sounds like you have been throwing a lot and a lot of different ferts at them.
Bruce

Bruce nailed it. Sun scald happens only around the time of plant out if they were not hardened off properly. It will look similar to chemical burn.

Thanks for the advice. I'll stop with the ferts for a while. Although, I had problems with blossom end rot on some tomatoes last year (all growing conditions are very similar this year), which is why I'm using Cal-mag plus this year. Should I stop the Cal-mag for now too? Or would it be safe to use a 1/2 strength mix of that?

I would stop it all. I am sure there is still enough in the soil to keep them more than happy.
Peppers don't normally need a whole lot of extra nutrients to grow well. I have only added ferts to mine twice this summer since putting them outside in mid May. I probably would have given them more, but we have had so much rain that I don't want to have to water to get them more nutrients. They are all doing fine.
Bruce

Thanks again for the help.