Trimming does not impact density of the buds. You have not 'shocked' or stressed it... it's dying or dead 24h after you harvest. Even if it did 'transport water, the effect you are describing simlpy doesn't happen. There is nothing that a living plant can do that causes such a massive change to the buds in a matter of hours and certainly not a half-dead plant. There must be some sort of mistake or misperception.
Buds shrink as they lose water-weight.