I’ve had the same problem happen on multiple grows where the bottom leaves get a little discoloration and presents these brown spots that you can see through. The only problem i had so far was fungus gnats, the plant looks healthy overall. I have good airflow, temperature ranging from 19 to 25 Celsius and humidity from 50% to 60% on most days and 70% on rainy days. I water every two days when the soil is dry the pot is light.
Can someone give me an insight about what could be the issue?
I'm feeding every two days, i first noticed around a week ago, but considering two plants are still vegging and one are flowering i believe it started before and i missed it.