I have a pretty low humidity when lights is on at ...

Hi @TheGreenFingers! We've all experienced high humidity at night, because when the lights are off the air remains wet and plants tend to sweat more at night. In a few words, yes it could become a problem, especially during late flowering when your buds are becoming fat & compact, there is a risk of mold/bud-rot. I was running through the same issue until I bought an electric dehumidifier. It's an investment (100~300$) but it will probably prevent your crop from rottening and save you months of hard labour. Plus, resin & terpenes tend to develop better in a low relative humidity environment, this is the other reason why we all want to decrease the RH during the late flowering stage. Hope this will help, keep us up-to-date and happy growing 👊