Brown spots and yellow leaves

EC value too high Soil too acidic Too much magnesium, potassium, or (especially) ammonium in the growing medium The growing medium binds calcium too strongly and doesn’t release it Humidity is too high or too low, negatively affecting the plant’s transpiration Keep us updated!

Lower leaves not getting enough light and going yellow is normal, the brown spots is a calcium deficiency. Plants do not direct/re-direct energy, this is one of the most misunderstood concepts regarding plant dynamics.

Not enough calcium. I would ease up on the nitrogen though and stop all further trimming. Your plant NEEDS those leaves to make the energy required for flower growing!

Looks to be the beginning of calcium issues. Plants will drop old leaves not getting exposed to light or if its to crowded. Plants look a bit over fed as well.

your plant is also praying super hard and looks super healthy and happy otherwise.

its natural. plants tend to cannabilize the older fan leaves. partially because they arent getting enough light and because theyve done their job already as the main fan leaves earlier on in the plants life cycle. in my experience even feeding more nitrogen wont correct it. its perfectly normal and the plant is just done using them and directing its energy elsewhere.