it does look like it's dried out from sunburn. Too much direct , hot sunlight on it perhaps. Try to move it somewhere or shield it somehow so it doesn't get worse

I am also thinking sunburn. Interesting how localized it is but not uncommon. Perhaps there is a reflection which concentrates sunlight in that area. Its a nuisance but some people like to use the cardboard rolls from paper towels to temporarily shield it until leaves come in and shade the area. Aluminum foil can work as well...both are pretty ugly but temporary.

Nice bloom to see. Thanks for posting it.

Sunburn on full sun plants. I'm at a loss. Does their bark toughen up eventually, or will this always be a problem?

Not full sun plants.

Especially when "young".

when they are young they can't shield themselves from burning sun with their leaves cause they don't have enough of them to actually drop enough shade on themselves. Large, older trees are fine in full sun as they already produced many branches with large amount of leaves that cover delicate areas from the sun... and yes, the bark will thicken up a bit over time.