I think I have a case on my top main cola, tips of some buds are turning white and some are turning brown and drying out, sucks balls, prolly gonna loose like 5 grams to it, heard the term bud rot before but still don't know what it means
How's your humidity? Pretty sure it's a result of high humidity, high temps, and bad ventilation. You need to cut off the infected parts asap before it keeps spreading. You can still salvage some of it but get in there and cut the nasty shit off as soon as you can. And be careful not to touch other parts of the plant after handling the moldy part. You'll spread spores and make it worse. You're in a bad situation if it's really about 5 grams effected like you said. It's probably a little worse than you think. It starts from within the bud. I'd definitely inspect your plant thoroughly.
Humidity and poor ventilation or air circulation causes this. The way I check for it is if I notice a suspect area, like odd yellowing then I find a little sugar leaf right in the middle of the bud and give it a little tug. If it comes out easily and, if where the stem meets the leaf, is brownish yellow with maybe some white fuzz then your fucked. If the leaf doesn't come out then you are probably alright, you can still check by peeling some buds back and looking at the inside of the cola. If you have mold then take drastic measures immediately, it can spread fast and ruin a while harvest in a week or two. Sulfur vaporizers work great but are not an option for everyone. Cut out the infected areas, add more fans to circulate air, address heat ventilation and humidity issues which are all usually related.
When lights and fan are on temp and humidity are good, I installed a little fan to suck air when the main is off so I shouldn't have this problem next time