Jupp, that are leafminers indeed. You can turn leaves to look if you see a small cocoon. You can crush it with your fingers.
But best would be if you remove the damaged leaves to make sure that it doesn't spread further. Don't put the leaves in the compost. Good look with your grow and wish you a good harvest
@Smoking_Joe_Frasier, thank you for the advice! I found and removed some leafminers on the backside of the leaves (they looked like little flies, light brown with pink eyes), sparyed a few times with tobacco water and cut off especially badly damaged leaves. Hopefully that helped as there is no more damage.
atout
