Humidity setting

It won't affect your young photoperiod plants at all.

Seedlings and young plants in veg don't really need crazy high humidity, you really only need to concern yourself with high humidity with clone cuttings before they root. On the flip side, in early flower mold generally isn't a big concern yet either. That's more of a concern mid to late flower when buds start fattening up.

Basically I have the same setup and wondered the very same question. I bought a dehumidifier that runs at night, during the day I got a constant 50-55% humidity level by opening a window. Like you do now I feared that the younger plants might be harmed by the lower humidity levels, yet the opposite was the case: the plants grow faster and appear more healthy. I think this is a result of more stable environmental conditions and a constant VPD. Remember, different strains have different needs. Try it out carefully, even though it worked out great for my strains it might still harm yours. Good thing about the photos is, even if they get harmed and grow slower, that you can just give them more time in veg before flipping (if you don't have 12/12 schedule from seed which I assume since you are also growing autos). Bud rot would be way worse and can completly ruin your harvest. Good luck mate and happy growing! 🌱