Are humidity fluctuations bad for the plants?

My cabinet stays at about 65% humidity on average without the humidifier on. When the humidifier runs it pretty quickly reaches 90%, so I turn it off. The cabinet then drops humidity fairly quickly back to 65-75% for a while. I’m assuming these extreme fluctuations stress the plants out, but so far they aren’t showing me signs of stress. Anyone have experience/knowledge on this?