Brown rot or sunburn?

Does anyone have advice on whether this is the beginning of brown rot, or if it is sunburn on my Superior plums? It doesn’t seem like brown rot because there are no conidia.

Also, I have read Monterey Fungi Fighter is one of the sprays that you can use for brown rot (a.i. = propiconazole), however, after checking it appears that product has been discontinued by Monterey.

However, Bonide has a similar product with bearing stone fruit on the label. I may have to add it to my program for next year.

I use the Bonide product with good results

But I think those fruits are too far gone to be saved!

Yeah… next year… Though the ones I have picked with the smallest amount of damage taste good once the damage is removed.