If you catch the mold early enough, can you cut it away from the bud and still salvage the rest of the bud?
Are you certain that you have bud rot? Some photographs would be helpful.
I’ve asked my partner to get us some pics. He’s a fairly experienced grower and has seen this before. But we’re open to any and all help.
I would do a peroxide bud wash with any bud you happen to save. Peroxide kills mold on contact and isn’t toxic if done properly.
Def can be salvaged. To be safe tho i would still chop the one bud. After rain or morning dew, good to grab stalk and give them a shake to help get the water off them. Or if really big plant…break out the leaf blower lol. Good luck