Hi
@Gaiizka your plant looks relatively fine except the lower yellowing leaves of coarse,
when you feed do you adjust the ph? It is important to try to keep your soil and especially what you feed them within a range of 6-7 on the ph chart. the reason for this is that plants like cannabis can get a nutrient lockout if the ph is too high or low and no matter how much you feed them they cannot access the nutrients if the ph is not within the required range. I hope I have helped don't worry about lower leaves dying off but if it spreads thruout the plant
you may have a bigger problem