I am not sure what this this brown spot is on the ...

My heart broke when I saw that. 💔 mold

This is what you call bud rot. The plant is slowly rotting away and will continue to do so all the way up and down that bud. Your best bet is to cut it all the way down to the bottom two buds you see at the bottom of the picture and throw it in the trash. This happens when there is a combination of high humidity and moisture accumulating on the plant and not enough airflow to dry it out. To prevent this, keep your humidity in check and add additional fans to the area. Hope this helps.

100% agree with mod. In addition to what he said, before you do an other run. You’re going to have to deep clean your tent and everything in it before you start again. Next run, you’ll also have to keep relative humidity down. I’m suspecting that you have had some higher temps and humidity during this run and this is the reason you’ve run into some bud rot issues. I’m sorry this happened to you, it’s definitely heartbreaking after putting so much time and effort into it.

Hey mate, sorry to say but your bud is probably rotting. Its definetly dead and mostly its because its rotting inside, if it didnt rot yet it will, because its dead material and perfect base for mold. This branch unfortunately is fcked and should go to trash.