O that sucks, this is bud rot 100% caused by Botrytis Cinerea
https://en.
wikipedia.org/wiki/Botrytis_cinerea
There is no cure or quick fix, you need to remove the affected buds asap and spray it down with peroxide to help deactivate the spores should be start to fly aorund. It would also be best to increase the ventilation in your tent and lower the humidity to under 40% to help deter this pesky mold from finding a sweet spot and growing. If you have any UV lights they can help kill off the spores as well.
I don't see a tent being used to grow these or a fan pushing air aorund them so this might be why it took root in your plant. a little preventive maintenance can go a long way but sometimes it just fucks us over.
Buds affected with rot can not be smoke or used in any way they are now garbage.
FYI: We will not be notified of any reply or tag [@] in the questions part of the website, if you need to reach out with other information use your DM "direct mailbox" in the bottom right hand corner of the page. it looks like a little paper airplane icon.
Best Of Luck!