Looks like an earlier layer - not sure when but it was dark bottom paint coming off and at times red paint left underneath, had been applied wrong - with a primer that hadn't bonded to the underlying paint.
Solution? 5k of sodablasting, in SD. Likely some fairing, and new primer and paint. The end result, looking on the positive side, is we'll lose ten years of bottom paint and its weight. Also we'll know that it's done right.
Still - annoying!
Don't look here
but still looks pretty if you don't look too close!