My humidity instant raises

transpiration.. as the plants get bigger they release more moisture. Ambient RH rose too, maybe?

I would check the position of the probe. and give it a test. like putting it in a jar with a RH packet and see if it registers what the pack says it is. give or take 5%. The only thing I could see if that the wounds of the plant are bleeding out and evaporating. but they should have healed up under 24hrs. Or the room your pulling air from is damp. like if a rain just happened or if your cooking and have been boiling a lot of water. Keep up the exhaust fan. test the ambient rooms RH and the probe its self. Good Luck!

After defoliation you should have humidity drop, not spike. Maybe exaust died or works on wrong regime. Your statement lacks logic. There should be something more ...

Are your ph right in the medium? Because if it’s not right the plan just evaporates the moist trough the leaves because it can’t take it up! So you get a very humid environment. Especially when you enter flower because the ph in ur medium are lowering when they start to flower. So you have to give them a little higher ph when they start to flower. So look over your ph, then balance it then I think your problem will get more stabilized. 😃💪🏽