THAT looks like the stem and center of the bud is involved. I’d get rid of the entire bud and then look the whole plant over hard. Look as deep into the buds as you can.
I’ve dealt with bud rot (botrytis), white powdery mildew and sooty mold this year. We have a stretch of pretty dry weather lately so maybe it will abate a little.
I’d hit the entire plant with Neem Oil spray, alternated with Diatomaceous Earth (food grade) dusting and then follow the Cervantes bud washing procedure at harvest. But, that’s just me and my plants. I claim no particular expertise and something else might work better for you.
In any event … it sucks, doesn’t it?
ETA: This post links the Cervantes video: