Mold or SpiderMite ?

That's fungus, and not a good one. Botrytis. You'll need to cut that all away, everything, that's near or around all that, leafs, the bud it was on, everything. Botryis as I said is a fungus, depending on your RH if high it spreads rapidly and quick, quick enough it'll ruin your crop overnight. So, to slow it down, increase ventilation as this will slow the spread down. Don't go cutting through buds as you would do with bud rot, as you can save a cola with bud rot, this is fungus. If was a by product of rot I'd be looking to see browning of the bud, shriveled up and so on. That's a healthy plant just in wrong conditions. If you have high RH you HAVE to make sure you have great ventilation. It is possible to grow in high RH without this. You just need good ventilation. So, everything that has it, needs to go, the surroundings and so on. You'd be better just cutting the bud from the stem, leafs and all attached. Any tools you use, make sure you wipe it down good. Then you want to make a h202 solution and spray where you can, try not get the buds wet, but it won't do any harm if you get a little. Clean the blades of fans and a general wipe down. Look into H202 flushing if it persists and flush your soil. Good luck